Answer:
A. The stepwise selection procedure uses Adjusted R-square as the "best" model criterion.
Step-by-step explanation:
Stepwise regression is a model which uses variables in step by step manner. The procedure involves removal or inclusion of independent variables one by one. It adds the most significant independent variable and removes the less significant independent variable. Usually stepwise selection uses R-square or Mallows Cp for picking the best fit.
How many pepperoni pizzas did they buy if they bought 6 cheese pizzas
Answer:
Question is incomplete but use below
Step-by-step explanation:
you can do total = (price of cheese pizza) ( amount of cheese pizzas bought)+(price of pepperoni pizza) ( amount of pepperoni pizzas bought)
15. What is the next number in this series?
6, 11, 9, 14, 12,
a. 17
b. 10
C. 18
d. 16
Answer:
a. 17
Step-by-step explanation:
The pattern is add 5 then subtract 2
Determine whether Rolle's Theorem can be applied to f on the closed interval
[a, b].
f(x) = −x2 + 3x, [0, 3]
Yes, Rolle's Theorem can be applied.No, because f is not continuous on the closed interval [a, b].No, because f is not differentiable in the open interval (a, b).No, because f(a) ≠ f(b).
If Rolle's Theorem can be applied, find all values of c in the open interval
(a, b)
such that
f '(c) = 0.
(Enter your answers as a comma-separated list. If Rolle's Theorem cannot be applied, enter NA.)
c =
Answer:
Yes, Rolle's theorem can be applied
There is only one value of c such that f'(c) = 0, and this is c = 1.5 (or 3/2 in fraction form)
Step-by-step explanation:
Yes, Rolle's theorem can be applied on this function because the function is continuous in the closed interval (it is a polynomial function) and differentiable in the open interval, and f(a) = f(b) given that:
[tex]f(0)=-0^2+3\,(0)=0\\f(3)=-3^2+3\,(3)=-9+9=0[/tex]
Then there must be a c in the open interval for which f'(c) =0
In order to find "c", we derive the function and evaluate it at "c", making the derivative equal zero, to solve for c:
[tex]f(x)=-x^2+3\,x\\f'(x)=-2\,x+3\\f'(c)=-2\,c+3\\0=-2\,c+3\\2\,c=3\\c=\frac{3}{2} =1.5[/tex]
There is a unique answer for c, and that is c = 1.5
Rolle's theorem is applicable if [tex]f(a)=f(b)[/tex] and $f$ is differentiable in $(a,b)$
since it's polynomial function, it's always continuous and differentiable..
and you can easily check that $f(0)=f(-3)=0$
so it is applicable.
now, $f'(x)=-2x+3=0 \implies x=\frac32$
there is only once value (as you can imagine, the graph will be downward parabola)
Multiply 750 x 38 step by step plzzz
Answer:
28500
Step-by-step explanation:
you simply set up a equation on paper then you solve it using the method where you put numbers under each other than multiply
Answer:
28500
Step-by-step explanation:
find the greatest common factor of 108d^2 and 216d
Answer:
Below
Step-by-step explanation:
If d is a positive number then the greatest common factor is 108d.
To get it isolate d and d^2 from the numbers.
108 divides 216. (216 = 2×108)
Then the greatest common factor of 216 and 108 is 108.
For d^2 and d we will follow the same strategy
d divides d^2 (d^2 = d*d)
Then the greatest common factor of them is d.
So the greatest common factor will be 108d if and only if d is positive. If not then 108 is the answer
Answer:
[tex]\boxed{108d}[/tex]
Step-by-step explanation:
Part 1: Find GCF of variables
The equation gives d ² and d as variables. The GCF rules for variables are:
The variables must have the same base.If one variable is raised to a power and the other is not, the GCF is the variable that does not have a power.If one variable is raised to a power and the other is raised to a power of lesser value, the GCF is the variable with the lesser value power.The GCF for the variables is d.
Part 2: Find GCF of bases (Method #1)
The equation gives 108 and 216 as coefficients. To check for a GCF, use prime factorization trees to find common factors in between the values.
Key: If a number is in bold, it is marked this way because it cannot be divided further AND is a prime number!
Prime Factorization of 108
108 ⇒ 54 & 2
54 ⇒ 27 & 2
27 ⇒ 9 & 3
9 ⇒ 3 & 3
Therefore, the prime factorization of 108 is 2 * 2 * 3 * 3 * 3, or simplified as 2² * 3³.
Prime Factorization of 216
216 ⇒ 108 & 2
108 ⇒ 54 & 2
54 ⇒ 27 & 2
27 ⇒ 9 & 3
9 ⇒ 3 & 3
Therefore, the prime factorization of 216 is 2 * 2 * 2 * 3 * 3 * 3, or simplified as 2³ * 3³.
After completing the prime factorization trees, check for the common factors in between the two values.
The prime factorization of 216 is 2³ * 3³ and the prime factorization of 108 is 2² * 3³. Follow the same rules for GCFs of variables listed above and declare that the common factor is the factor of 108.
Therefore, the greatest common factor (combining both the coefficient and the variable) is [tex]\boxed{108d}[/tex].
Part 3: Find GCF of bases (Method #2)
This is the quicker method of the two. Simply divide the two coefficients and see if the result is 2. If so, the lesser number is immediately the coefficient.
[tex]\frac{216}{108}=2[/tex]
Therefore, the coefficient of the GCF will be 108.
Then, follow the process described for variables to determine that the GCF of the variables is d.
Therefore, the GCF is [tex]\boxed{108d}[/tex].
how many solutions does −6+2x=3x have?
Answer:
one solution
Step-by-step explanation:
−6+2x=3x
Subtract 2x from each side
−6+2x-2x=3x-2x
-6 = x
There is one solution
Answer:
it has 1 answer :)
Step-by-step explanation:
Given the following three points, find by the hand the quadratic function they represent (0,6, (2,16, (3,33)
Answer:
[tex] f(x) = 4x^2 - 3x + 6 [/tex]
Step-by-step explanation:
Quadratic function is given as [tex] f(x) = ax^2 + bx + c [/tex]
Let's find a, b and c:
Substituting (0, 6):
[tex] 6 = a(0)^2 + b(0) + c [/tex]
[tex] 6 = 0 + 0 + c [/tex]
[tex] c = 6 [/tex]
Now that we know the value of c, let's derive 2 system of equations we would use to solve for a and b simultaneously as follows.
Substituting (2, 16), and c = 6
[tex] f(x) = ax^2 + bx + c [/tex]
[tex] 16 = a(2)^2 + b(2) + 6 [/tex]
[tex] 16 = 4a + 2b + 6 [/tex]
[tex] 16 - 6 = 4a + 2b + 6 - 6 [/tex]
[tex] 10 = 4a + 2b [/tex]
[tex] 10 = 2(2a + b) [/tex]
[tex] \frac{10}{2} = \frac{2(2a + b)}{2} [/tex]
[tex] 5 = 2a + b [/tex]
[tex] 2a + b = 5 [/tex] => (Equation 1)
Substituting (3, 33), and c = 6
[tex] f(x) = ax^2 + bx + x [/tex]
[tex] 33 = a(3)^2 + b(3) + 6 [/tex]
[tex] 33 = 9a + 3b + 6 [/tex]
[tex] 33 - 6 = 9a + 3b + 6 - 6 [/tex]
[tex] 27 = 9a + 3b [/tex]
[tex] 27 = 3(3a + b) [/tex]
[tex] \frac{27}{3} = \frac{3(3a + b)}{3} [/tex]
[tex] 9 = 3a + b [/tex]
[tex] 3a + b = 9 [/tex] => (Equation 2)
Subtract equation 1 from equation 2 to solve simultaneously for a and b.
[tex] 3a + b = 9 [/tex]
[tex] 2a + b = 5 [/tex]
[tex] a = 4 [/tex]
Replace a with 4 in equation 2.
[tex] 2a + b = 5 [/tex]
[tex] 2(4) + b = 5 [/tex]
[tex] 8 + b = 5 [/tex]
[tex] 8 + b - 8 = 5 - 8 [/tex]
[tex] b = -3 [/tex]
The quadratic function that represents the given 3 points would be as follows:
[tex] f(x) = ax^2 + bx + c [/tex]
[tex] f(x) = (4)x^2 + (-3)x + 6 [/tex]
[tex] f(x) = 4x^2 - 3x + 6 [/tex]
PLEASE PLEASE PLEASE HELP ME ANSWER THIS QUESTION QUICK!! The picture of the question is down below. The answer choices are increased or decreased.
Answer:
NEGATIVE; DECREASED.
Step-by-step explanation:
A correlation coefficient of -0.76 indicates that there is a "fairly" strong negative relationship between the daily temperature and the number of people who visit the store.
This implies that, as the daily temperature increases, number of customers who come to the store decreases.
Therefore, the interpretation of the situation is:
"There is a NEGATIVE association between x and y. As the high temperature of the day increases across days, the number of customers who come to the store DECREASED.
The area of the circle x² + y2 - 6x-4y +9 = 0 is
Answer:
Your answer is here.Enjoy dude
Answer:
12.56 unit²
Step-by-step explanation:
Given:x² + y² - 6x - 4y + 9 = 0To find:The area of circleSolution:The form of the circle is:
(x- h)² + (y-k)² = r²Let's bring the given to the form of a circle as above:
x² + y² - 6x - 4y + 9 = 0x² - 6x + y²- 4y + 9 = 0 ⇒ combining like terms and completing squarex² - 6x + 9 + y²- 4y + 4 = 4 ⇒ adding 4 to both sides(x-3)² + (y - 2)² = 2² ⇒ got the form of this circleAs per the form, we got r² = 2², so the radius of circle is 2 units.
The area of circle:
A= πr² = 3.14×2² = 12.56 unit²use a paragraph, flow chart, or two column proof to prove the angle congruency
Answer: see proof below
Step-by-step explanation:
Statement Reason
1. ∠CAX ≅ ∠ BAX 1. Given
2. AC ≅ AB 2. Given
3. AY ≅ AY 3. Reflexive Property
4. ΔCAY ≅ ΔBAY 4. SAS Congruency Theorem
5. CY ≅ BY 5. CPCTC
6. ∠CYA ≅ ∠BYA 6. CPCTC
7. ∠CXY ≅ ∠ BXY 7. Given
8. ΔCYX ≅ ΔBYX 4. AAS Congruency Theorem
9. ∠XCY ≅ ∠XBY 9. CPCTC
Step-by-step explanation:
Hope it helps u
plz mark it as brainlist
A doctor orders Quinidine for an adult patient weighing 110 lb at a dosage of 25 mg/kg/day q6h. How many
milligrams should the patient receive each day?
Answer:
Total amount receive each day = 1250 mg per day
Number of dosage = 1250 / 4 = 312.5 mg per meal
Step-by-step explanation:
Given:
Weight of patient = 110 lb
Dosage = 25 mg/kg/day
Find:
Total amount receive each day
Computation:
Weight of patient = 110 lb
1 lb = 0.453592
Weight of patient = 110 (0.453592)
Weight of patient = 49.89
Weight of patient = 50 kg (Approx)
Total amount receive each day = 50 kg × 25 mg/kg/day
Total amount receive each day = 1250 mg per day
Number of dosage = 1250 / 4 = 312.5 mg per meal
Ashley, Milan, and Carlos sent a total of 131 text messages over their cell phones during the weekend. Carlos sent 7 times as many messages as Ashley. Ashley sent 4 more messages than Milan. How many messages did they each send?
Answer:
Ashley= 15
Milan= 11
Carlos= 105
Step-by-step explanation:
Let, A, M and C denotes Ashley, Milan and Carlos respectively.
A+M+C= 131 (according to the question)
Here,
C= 7A
A= M+ 4
So, M= A - 4
Now,
A+M+C = 131
or, A+ A-4+ 7A = 131 (putting the values)
or, 9A - 4 = 131 (adding like terms i.e. A + A + 7A)
or, 9A = 131 + 4
or, 9A = 135
or, A = 135 / 9
So, A = 15
C= 7A = 7×15= 105
M= A-4 = 15 - 4 = 11
Identify the decimals labeled with the letters A, B, and C on the scale below. Letter A represents the decimal Letter B represents the decimal Letter C represents the decimal
[tex]10[/tex] divisions between $389$ and $390$ so each division is $\frac{390-389}{10}=0.1$
A is 8 division from $389$, so, A is $389+8\times 0.1=389.8$
similarly, C is one division behind $389$ so it is $389-1\times 0.1=388.9$
and B is $390.3$
There were 120 planes on an airfield. if 75% of the plane took off for a flight, how many planes took off?
Answer:
90 planes
Step-by-step explanation:
Take the total number of planes and multiply by the percentage of planes that took off
120 * 75%
120 * .75
90
a. Assume that the selections are made with replacement. Are the events independent? The probability of getting two orders from Restaurant D is . The events (1) independent because choosing the first order (2) the choice of the second order. (Round to four decimal places as needed.) b. Assume that the selections are made without replacement. Are the events independent? The probability of getting two orders from Restaurant D is . The events (3) independent because choosing the first order (4) the choice of the second order.
Answer: = a = 0.0206
b = 0.0205.
Step-by-step explanation:
From the question, given that;
Order Accurate = 328 273 242 142
Order Not Accurate = 32 54 37 20
Let us make the Total orders given be
T.O = 328+273+242+142+32+54+37+20 = 1128.
a) Let the Prob. that the first order is from restaurant D be
= Number of order from restaurant D / Total number of orders
= 162 / 1128 = 0.1436
Probability of the second order is 0.1436.
This is because, from the question we can tell that the selections are made with replacement, that means the order is the same.
So, the probability of getting 2 orders =
= 0.1436 * 0.1436 = 0.0206
NB: The probability of getting two orders from restaurant B is 0.0206.
This is because choosing the first order does not affect the second order
(independent events).
b) Assuming that the selections are made without replacement , the probability of getting both the orders from restaurant D =
Probability of getting 1st order from restaurant D = 162/1128 = 0.1436.Probability of getting 2nd order from restaurant D = 161 / 1127 = 0.1428This gives the Total Probability of getting both the orders from restaurant D, without replacement to be = 0.1436*0.1428
= 0.0205.
That is to say choosing the first order affects the second order because of the events are not independent as compared to the first question.
cheers i hope tis helps
Maya is interning at a law firm over the summer and is paid b the hour. If her hourly wage is $52 which represents the proportional relationship between the wages she earns (w) and the number of hours (h)?
Answer: [tex]w= 52 h[/tex] .
Step-by-step explanation:
Given: Maya is interning at a law firm over the summer and is paid per hour.
Total wages = (Hourly wage) x (Number of hours worked)
If her hourly wage is $52, then the total wages(w) = 52 x (Number of hours(h))
i.e. w= 52 h
Hence, the proportional relationship between the wages she earns (w) and the number of hours (h) described by [tex]w= 52 h[/tex] .
Find the volume of this composite figure. Show all work.
Please!!!!!
Answer:
718.75ft³
Step-by-step explanation:
Rectangular Prism=5x5x17.5=437.5
Cube=5x5x5=125
Triangular Prism=5x5x12.5x.5=156.25
437.5+125+156.25=718.75ft³
All sacks of sugar have the same weight. All sacks of flour also have the same weight, but not necessarily the same as the weight of the sacks of sugar. Suppose that two sacks of sugar together with three sacks of flour weigh no more than 40 pounds and that the weight of a sack of flour is no more than 5 pounds more than the weight of two sacks of sugar. What is the largest possible weight (in pounds) of a sack of flour?
Answer:
The largest possible weight of flour is 11.25 pounds.
Step-by-step explanation:
To start with, we will assume that the weight of 1 sack of sugar = x pounds
We will also assume that the weight of 1 sack of flour = y pounds
So, the weight of 2 sacks of sugar = 2 * (x) = 2x
Same thing goes for the weight of 3 sacks of flour = 3 * (y) = 3y
Supposing that the weight of (2 sacks of sugar + 3 sacks of flour) ≤ 40 pounds
= 2x + 3y ≤ 40............ we'll call that equation 1.
Also, suppose that the weight of ( 1 sack of flour) ≤ 2 sacks of sugar + 5 pounds
= y ≤ 2x + 5........................ we'll call that equation 2
Therefore, we'll solve for the values of x and y in the two equations and we will get:
2x + 3y ≤ 40
y ≤ 2x + 5
Now, substitute the value of y into equation 1
2x + 3y ≤ 40 ⇒ 2x + 3(2x +5) =40
⇒ 2x + 6x + 15= 40
⇒ 8x + 15 = 40
⇒ 8x = 25
⇒ x = 25/8
⇒ x = 3.12
x cannot be more than 3.12 pounds, so we solve for y
Putting the value of x into equation 2, we'll get
⇒ 2y + 5 = 2(3.12) + 5
⇒ y = 11.25 pounds.
So, n cannot be more than 11.25 pounds
Please Show Work
Need Help
Answer:
The distance is 87.5 miles
Step-by-step explanation:
We can use a ratio to solve
1 in 3.5 inches
----------- = ----------------
25 miles x miles
Using cross products
1x = 3.5 * 25
x =87.5
The distance is 87.5 miles
━━━━━━━☆☆━━━━━━━
▹ Answer
87.5 miles
▹ Step-by-Step Explanation
[tex]\frac{1}{25} * \frac{3.5}{x} \\\\1 * 3.5 = 3.5\\25 * 3.5 = 87.5 \\\\Actual Distance = 87.5 miles[/tex]
Hope this helps!
CloutAnswers ❁
━━━━━━━☆☆━━━━━━━
Can Someone please explain this, please. Tell me how do I start the problem Thanks!
Answer:
x = 35, y = 15°
Step-by-step explanation:
6. Since ΔRST ≅ ΔXYZ, RT = XZ because of CPCTC which means:
x + 21 = 2x - 14
-x = -35
x = 35
7. Again, since ΔRST ≅ ΔXYZ, ∠R ≅ ∠X because of CPCTC which means:
4y - 10 = 3y + 5
y = 15°
Which of the following is NOT true?
A. 5x + 6x = 70 degrees
B. 5x + 6x < 180 degrees
C. 5x + 6x = 110 degrees
D. 5x + 6x + 70 degrees = 180 degrees
Please include ALL work! <3
Answer:
A. 5x + 6x = 70 degrees
Step-by-step explanation:
5x + 6x = 110 degrees because the sum of two interior angles in a triangle is equal to an exterior angle.
The value of y varies directly with x . Find the value of k when y 33.6 and x = 4.2
Answer:
k=8
Step-by-step explanation:
Since y and x are in direct proportions, the equation is
y= kx, where k is a constant.
when y= 33.6, x=4.2,
33.6= k(4.2)
k= 33.6 ÷4.2
k=8
Answer:
k=8
Step-by-step explanation:
what is the average rate of change from 1 to 3 of the function represented by the graph? the graph is attached.
Answer: -4
At 1, the parabola is at (1, 3). And at 3, it's at (3, -5). The rate of change is -4, since each time it moves right 1, it goes down 4.
Hope that helped,
-sirswagger21
An experimental probability is ______ likely to approach the theoretical probability if the number of trials simulated is larger. A. as B. more C. less D. not
Answer:
I believe your answer is b. the more trials you conduct, the more information you have
An experimental probability is more likely to approach the theoretical probability if the number of trials simulated is larger. Then the correct option is B.
What is probability?Its basic premise is that something will almost certainly happen. The percentage of favorable events to the total number of occurrences.
Experimental probability: A probability that is established from the findings of several iterations of a test.
Theoretical probability: The proportion of positive consequences to all potential outcomes. The ratio of the favorable event to the total event.
An experimental probability is more likely to approach the theoretical probability if the number of trials simulated is larger.
Then the correct option is B.
More about the probability link is given below.
https://brainly.com/question/795909
#SPJ2
Evaluate the limit, if it exists. (If an answer does not exist, enter DNE.). lim h → 0 1 + h − 1 h
Answer:
1Step-by-step explanation:
Given the limit of a function [tex]\lim_{h \to 0} \frac{(1+h)-1}{h}[/tex], to evaluate the limit, the following steps must be taken.
Step 1: Substitute h = 0 into the function given.
[tex]= \lim_{h \to 0} \frac{(1+h)-1}{h}\\\\[/tex]
[tex]= \frac{(1+0)-1}{0}\\\\= \frac{1-1}{0} \\\\= \frac{0}{0} (indeterminate)\\[/tex]
Step 2: Apply l'hospital rule
[tex]\lim_{h \to 0} \frac{\frac{d}{dh}[(1+h)-1] } {\frac{d}{dh}(h) } \\\\= \frac{0+1-0}{1}\\ \\= \frac{1}{1} \\ \\= 1[/tex]
Hence the limit of the function [tex]\lim_{h \to 0} \frac{(1+h)-1}{h} \ is \ 1[/tex]
BOND VALUATION Asiana Fashion's bonds have 10 years remaining to maturity. Interest is paid annually; they have a $1,000 par value; the coupon interest rate is 8% and thebyield to maturity is 9%.What is the bond's current market price?
Answer:
$935.76
Step-by-step explanation:
BOND VALUATION Asiana Fashion's bonds have 10 years remaining to maturity. Interest is paid annually; they have a $1,000 par value; the coupon interest rate is 8% and thebyield to maturity is 9%.What is the bond's current market price?
Step 1
We find the Present value factor of sum
The formula =
(1 + i)^n
Where
i = maturity rate = 9% = 0.09
n = number of years = 10 years
Present Value = ( 1 + 0.09)^-10
= 0.4224
Step 2
We find the present value factor of annuity
The formula is given as:
1 - (1+i)^-n / i
i = maturity rate = 9% = 0.09
n = number of years = 10 years
= 1 - (1 + 0.09)^-10 /0.09
= 1 - 0.4224 /0.09
= 0.5775 /0.09
= 6.417
Step 3
The bond's current market price is calculated as:
= PV factor of Sum × Par Value + PV factor of annuity × coupon payment
Coupon payment is calculated as:
= Coupon interest × par value
= 8% × 1000
= 80
Hence,
= 0.4224 × 1,000 + 6.417 × 80
= 422.4 + 513.36
= 935.76
In this exercise we have to use the knowledge of finance to calculate the corrective value of the market place, in this way we find that:
[tex]\$935.76[/tex]
We find the Present value factor of sum, by the formula of:
[tex](1 + i)^n[/tex]
Where:
i = maturity rate = 9% = 0.09 n = number of years = 10 years
Substituting the values in the formula as;
[tex]Present \ Value = ( 1 + 0.09)^{-10} = 0.4224[/tex]
We find the present value factor of annuity, by the formula as:
[tex]1 - (1+i)^{-n} / i[/tex]
Where:
i = maturity rate = 9% = 0.09 n = number of years = 10 years
Substituting the values in the formula as;
[tex]= 1 - (1 + 0.09)^{-10} /0.09\\= 1 - 0.4224 /0.09\\= 0.5775 /0.09\\= 6.417[/tex]
The bond's current market price is calculated as:
[tex]= PV \ factor\ of\ Sum * Par\ Value + PV\ factor\ of\ annuity * coupon\ payment[/tex]
Coupon payment is calculated as:
[tex]= Coupon\ interest * par\ value\\= 8\% * 1000= 80[/tex]
So continue the calcule;
[tex]= 0.4224 *1,000 + 6.417 * 80\\= 422.4 + 513.36\\= 935.76[/tex]
See more about market place at brainly.com/question/24518027
18x + 7, when x = 2
Answer:
43
Step-by-step explanation:
18x+7
=18×2+7
=36×9
=45
Answer:
43
Step-by-step explanation:
x=2
18x+7
18(2)+7
36+7
43
Hope this helps ;) ❤❤❤
In a stable matching problem, if every man has a different highest-ranking woman on his preference list, and given that women propose, then it is possible that, for some set of women's preference lists, all men end up with their respective highest-ranking woman.a. Trueb. False
Answer:
True
Step-by-step explanation:
The statement given above in the question is correct. It is mentioned that men are free to create a list of women's according to their preferences. There will be order sequence of women and men places them in queue of their preference. The men proposes the women with highest ranking in the list then it is possible that all men gets their preferred choice.
Nina skated for 2 hours and 14 min she stop at 8:24 pm when did Nina start skating
Answer:
6:10
Step-by-step explanation:
The lengths of pregnancies in a small rural village are normally distributed with a mean of 265 days and a standard deviation of 14 days. In what range would we expect to find the middle 50% of most lengths of pregnancies
Answer:
the middle 50% of most lengths of pregnancies ranges between 255.62 days and 274.38 days
Step-by-step explanation:
Given that :
Mean = 265
standard deviation = 14
The formula for calculating the z score is [tex]z = \dfrac{x -\mu}{\sigma}[/tex]
x = μ + σz
At middle of 50% i.e 0.50
The critical value for [tex]z_{\alpha/2} = z_{0.50/2}[/tex]
From standard normal table
[tex]z_{0.25}=[/tex] + 0.67 or -0.67
So; when z = -0.67
x = μ + σz
x = 265 + 14(-0.67)
x = 265 -9.38
x = 255.62
when z = +0.67
x = μ + σz
x = 265 + 14 (0.67)
x = 265 + 9.38
x = 274.38
the middle 50% of most lengths of pregnancies ranges between 255.62 days and 274.38 days
