25. Approximate the sample variance and standard deviation given the following frequency distribution: Class Frequency 0–9 13 10–19 7 20–29 10 30–39 9 40–49 11
Answers
Sample variance = 228.408
Standard deviation = 15.113
Step-by-step explanation:The well formatted frequency table has been attached to this response.
To calculate the sample variance and standard deviation of the given grouped data, follow these steps:
i. Find the midpoint (m) of the class interval.
This is done by adding the lower bounds and upper bounds of the class intervals and dividing the result by 2. i.e
For class 0 - 9, we have
m = (0 + 9) / 2 = 4.5
For class 10 - 19, we have
m = (10 + 19) / 2 = 14.5
For class 20 - 29, we have
m = (20 + 29) / 2 = 24.5
For class 30 - 39, we have
m = (30 + 39) / 2 = 34.5
For class 40 - 49, we have
m = (40 + 49) / 2 = 44.5
This is shown in the third column of the attached table.
ii. Find the product of each of the frequencies of the class intervals and their corresponding midpoints. i.e
For class 0 - 9, we have
frequency (f) = 13
midpoint (m) = 4.5
=> f x m = 13 x 4.5 = 58.5
For class 10 - 19, we have
frequency (f) = 7
midpoint (m) = 14.5
=> f x m = 7 x 14.5 = 101.5
For class 20 - 29, we have
frequency (f) = 10
midpoint (m) = 24.5
=> f x m = 10 x 24.5 = 245
For class 30 - 39, we have
frequency (f) = 9
midpoint (m) = 34.5
=> f x m = 9 x 34.5 = 310.5
For class 40 - 49, we have
frequency (f) = 11
midpoint (m) = 44.5
=> f x m = 11 x 44.5 = 489.5
This is shown in the fourth column of the attached table.
iii. Calculate the mean (x) of the distribution i.e
This is done by finding the sum of all the results in (ii) above and dividing the outcome by the sum of the frequencies. i.e
x = ∑(f x m) ÷ ∑f
Where;
∑(f x m) = 58.5 + 101.5 + 245 + 310.5 + 489.5 = 1205
∑f = 13 + 7 + 10 + 9 + 11 = 50
=> x = 1205 ÷ 50
=> x = 24.1
Therefore, the mean is 24.1
This is shown on the fifth column of the attached table.
iv. Calculate the deviation of the midpoints from the mean.
This is done by finding the difference between the midpoints and the mean. i.e m - x where x = mean = 24.1 and m = midpoint
For class 0 - 9, we have
midpoint (m) = 4.5
=> m - x = 4.5 - 24.1 = -19.6
For class 10 - 19, we have
midpoint (m) = 14.5
=> m - x = 14.5 - 24.1 = -9.6
For class 20 - 29, we have
midpoint (m) = 24.5
=> m - x = 24.5 - 24.1 = 0.4
For class 30 - 39, we have
midpoint (m) = 34.5
=> m - x = 34.5 - 24.1 = 10.4
For class 40 - 49, we have
midpoint (m) = 44.5
=> m - x = 44.5 - 24.1 = 20.4
This is shown on the sixth column of the attached table.
v. Find the square of each of the results in (iv) above.
This is done by finding (m-x)²
For class 0 - 9, we have
=> (m - x)² = (-19.6)² = 384.16
For class 10 - 19, we have
=> (m - x)² = (-9.6)² = 92.16
For class 20 - 29, we have
=> (m - x)² = (0.4)² = 0.16
For class 30 - 39, we have
=> (m - x)² = (10.4)² = 108.16
For class 40 - 49, we have
=> (m - x)² = (20.4)² = 416.16
This is shown on the seventh column of the attached table.
vi. Multiply each of the results in (v) above by their corresponding frequencies.
This is done by finding f(m-x)²
For class 0 - 9, we have
=> f(m - x)² = 13 x 384.16 = 4994.08
For class 10 - 19, we have
=> f(m - x)² = 7 x 92.16 = 645.12
For class 20 - 29, we have
=> f(m - x)² = 10 x 0.16 = 1.6
For class 30 - 39, we have
=> f(m - x)² = 9 x 108.16 = 973.44
For class 40 - 49, we have
=> f(m - x)² = 11 x 416.16 = 4577.76
This is shown on the eighth column of the attached table.
vi. Calculate the sample variance.
Variance σ², is calculated by using the following relation;
σ² = ∑f(m-x)² ÷ (∑f - 1)
This means the variance is found by finding the sum of the results in (vi) above and then dividing the result by one less than the sum of all the frequencies.
∑f(m-x)² = sum of the results in (vi)
∑f(m-x)² = 4994.08 + 645.12 + 1.6 + 973.44 + 4577.76 = 11192
∑f - 1 = 50 - 1 = 49 {Remember that ∑f was calculated in (iii) above}
∴ σ² = 11192 ÷ 49 = 228.408
Therefore, the variance is 228.408
vii. Calculate the standard deviation
Standard deviation σ, is calculated by using the following relation;
σ =√ [ ∑f(m-x)² ÷ (∑f - 1) ]
This is done by taking the square root of the variance calculated above.
σ = [tex]\sqrt{228.408}[/tex]
σ = 15.113
Therefore, the standard deviation is 15.113
Related Questions
Due to the heavy rains, all pallets of blocks have become wet and the weight of each block has altered. It is desired to estimate the average weight of the blocks thus wet. For this, a sample of 15 blocks is selected and the following weights are recorded in kilograms: 45.8, 43.9, 46.2, 48.5, 47.2, 45.8, 49.1, 43.9, 47.6, 42.8, 46.5, 44.9, 46.8, 45.8 and 44.6; Estimate µ, the average weight of all pallets of blocks, and determine a bound for the estimation error.
Answers
Answer:
To find the estimated value we add all of them together then divide it by the amount of them
45.8+43.9+46.2+48.5+47.2+45.8+49.1+43.9+47.6+42.8+46.5+44.9+46.8+45.8 +44.6=689.4
now we divide it by 15 since there is 15 blocks so
689.4 divided by 15=45.96
so the average weight is 45.96
Match each expression with the correct description.
Answers
Which graph shows a dilation
Answers
Answer:
show the graphs?
Step-by-step explanation:
PLEASE HELP I WILL GIVE BRAINLIEST AND 25 POINTS!!!
The following function represents the value of a truck, in dollars, after x years:
f(x) = 29,000(0.88)x
What does 0.88 represent?
The decrease in the value of the truck, which is 12%
The present value of the truck
The value of the truck after x years
The decrease in the value of the truck, which is 88%
Answers
9514 1404 393
Answer:
(a) The decrease in the value of the truck, which is 12%
Step-by-step explanation:
The only reasonable choice among the offered answers is the one shown above.
__
We would describe the value 0.88 as the annual multiplier of the truck's value, which decreases 12% each year.
Which statement is true regarding the graphed functions?
Answers
Answer:
I am pretty sure that it's the second one
Tập nghiệm của phương trình 2^x=-1 là
Answers
Step-by-step explanation:
Tập nghiệm của [tex]2^x=-1[/tex] là tập rỗng nha bạn. Vì 2 là số dương nên mũ mấy cũng dương hết.
Find the area of the rectangle if the perimeter is 52 cm
Answers
Answer:
No solution is possible from the information provided
Step-by-step explanation:
What is the HFC of the following: 4 (x2-x+1) and 28 (x3+1)?
Answers
Your Answer is in the above image.
Which of these graphs represents a function?
Answers
Answer:
[tex]{ \tt{graph \: y \:and \:graph\: z}}[/tex]
Given m||n, find the value of x.
Answers
Q3a) How many lengths of string, each 53 cm
long can be cut from a ball containing 25
meters? (2 mks)
b) What length of string, in millimeters
remains? (2 mks)
Answers
Part (a)
1 meter = 100 cm
25 meters = 2500 cm .... multiply both sides by 25
Divide the 2500 cm over the 53 cm to get 2500/53 = 47.1698
Ignore the stuff after the decimal point. This means we can cut exactly 47 smaller bits of string, each 53 cm long
Answer: 47====================================================
Part (b)
We found that we can cut exactly 47 smaller bits of string, each 53 cm long. That takes up 47*53 = 2491 cm overall
The leftovers would be 2500 - 2491 = 9 cm which isn't longer than 53 cm
Convert 9 cm to mm by multiplying by 10 (because 1 cm = 10 mm).
9 cm = 90 mm
Answer: 90 mmWhich of the quadratic functions has the narrowest graph?
y = 2x^2
y = –x^2
y = 1/8x^2
y = 1/6x^2
Answers
A quadratic function's graph being wide or narrow is determined or depended on a-term:
[tex] \large{y = a {x}^{2} + bx + c}[/tex]
If |a| has a lot of value, for example a = 2 or a = 100. The graph will get narrower if increasing the value of |a|. On the other hand, If |a| has small value, for example a = 1/2 or a = 1/10000. The graph would be wide.
Also it does not matter if a-term is negative or not since a-term being positive or negative determines if a parabola is upward or downward. Only |a| determines how narrow/wide the graph is.
From the question, it is clear that the parabola y = 2x^2 is the narrowest graph since it has the highest |a| value out of all choices.
Answer
y = 2x^2What is the non-negative zero of the function f, where f(x) = 6x^2-9x-6?
Answers
Answer:
The non-negative zero of the function f(x) is x = 2.
Step-by-step explanation:
For a given function f(x), the "zeros" of the function are the values of x such that:
f(x) = 0
In this case, we have the function:
f(x) = 6*x^2 - 9*x - 6
If we want to find the zeros of this function, we need to solve:
f(x) = 0 = 6*x^2 - 9*x - 6
To solve this, we can use the Bhaskara's formula, which says that for a general quadratic equation:
0 = a*x^2 + b*x + c
The zeros are:
[tex]x = \frac{-b \pm \sqrt{b^2 - 4*a*c} }{2*a}[/tex]
In this case our equation is:
0 = 6*x^2 - 9*x - 6
then, in the above notation, we have:
a = 6
b = -9
c = -6
Replacing these in our general formula, we get:
[tex]x = \frac{-(-9) \pm \sqrt{(-9)^2 - 4*6*(-6)} }{2*6} = \frac{9 \pm 15 }{12}[/tex]
Then we have two zeros:
x = (9 + 15)/12 = 24/12 = 2
x = (9 - 15)/12 = -6/12 = -1/2
But we want only the non-negative, so we can discard the second one.
Concluding, the non-negative zero of the function f(x) is x = 2.
Casandra wants to buy a dress. She had of the money. Her mom gave her $120.00 but she was still short of the cost of the dress. What is the price of the dress?
Answers
I dont think I can be answered with just the given info... is some of the q missing still?
Closest we can do with above is dress cost = 120+ c
please solve in the next 10 minutes pleaseeee
Answers
Answer:
43.82 mph
266.67 feet
Step-by-step explanation:
Given :
S = √30fl
S = speed of car
f = drag Coefficient
l = Length of skid mark
If f = 0.8 ; l = 80 feets
s = √30fl
s = √(30*0.8*80)
s = √1920
s = 43.817
s = 43.82 mph
B.)
s = 80 mph
f = 0.8
s = √30fl
80 = √30*0.8*l
80 = √24l
Square both sides
80² = 24l
6400 = 24l
l = 6400/24
l = 266.67 feets
A group of campers is going to occupy 6 campsites at a campground. There are 16 campsites from which to choose. In how many ways can the campsites be chosen?
Answers
Answer:
The campsites can be chosen in 5,765,760 different ways.
Step-by-step explanation:
Given that a group of campers is going to occupy 6 campsites at a campground, and there are 16 campsites from which to choose, to determine in how many ways the campsites can be chosen, the following calculation must be performed:
16 x 15 x 14 x 13 x 12 x 11 = X
240 x 182 x 132 = X
240 x 24,024 = X
5,765,760 = X
Therefore, the campsites can be chosen in 5,765,760 different ways.
Consider the following graph:
What is the limit as it is approaching -1 from the right, what is the limit?
Answers
Answer:
The limit is 0, and the answer is given by option E.
Step-by-step explanation:
Limit to the right:
The limit of a function approacing a value of x to the right is given by the value of the function quite close to the point, looking to the right.
In this question:
Approacing by the right(x quite close, but more than -1, that is, -0.9999...), y tends to 0, so the limit is 0, and the answer is given by option E.
Will mark Brainlest helppp plllllssss
Answers
Answer:
2h
Step-by-step explanation:
f(3 + h) = 2(3 + h)^2 + 1
= 2(3^2 + h^2) + 1
= 2(9) + 2h^2 + 1
= 18 + 2h^2 + 1
= 2h^2 + 19
f(3) = 2(3)^2 + 1
= 2(9) + 1
= 18 + 1
= 19
2h^2 + 19 - 19 / h
2h^2 / h
2h
I need help I’ll mark u as brainlest
Answers
Answer:
V = 64 in^3
Step-by-step explanation:
The volume of a cube is given by
V = s^3 where s is the side length
V = 4^3
V = 64 in^3
Answer:
64
Step-by-step explanation:
volume of a cube formula: V = a^3
a is just one of the edges
[tex]4^{3}[/tex] = 64 = V
:)
Consider the given statements below.
• A central angle in a circle measures 70°.
An inscribed angle in the same circle also measures 70°.
Which statement best describes the relationship between the arcs
intersected by these angles?
.
1 of 4 QUESTIONS
The inscribed angle intersects an arc that is twice the measure of the arc
intersected by the central angle. The inscribed angle's arc measures 70°,
and the central angle's arc measures 35º.
The inscribed angle intersects an arc that is half the measure of the arc
intersected by the central angle. The inscribed angle's arc measures 35º,
and the central angle's arc measures 70°.
The inscribed angle intersects an arc that is half the measure of the arc
O intersected by the central angle. The inscribed angle's arc measures 70°
and the central angle's arc measures 140°.
The inscribed angle intersects an arc that is twice the measure of the arc
O intersected by the central angle. The inscribed angle's arc measures 140°,
and the central angle's arc measures 70°.
Answers
Answer:
1-90
2-80
3-033
Step-by-step explanation:
(Right angle) Trigonometry
please help!
Answers
Answer:
A = 41.4°
Step-by-step explanation:
Reference angle = A
Length of Adjacent side = 6
Length of Hypotenuse = 8
Apply the trigonometric function, CAH.
Cos A = Adj/Hyp
Substitute
[tex] Cos(A) = \frac{6}{8} [/tex]
[tex] A = Cos^{-1}(\frac{6}{8}) [/tex]
A = 41.4° (approximated to the nearest tenth)
Write .125 as a fraction reduced to lowest terms.
Answers
Answer:
1/8
Step-by-step explanation:
Hope this helps you! <33
Answer:
1/8
Step-by-step explanation:
We all know 1/2 is 0.5, right?
If you split that in half again, you get 0.25 as 1/4.
If you divide that again by two, you get 1/8 as 0.125
Need help with this question
Answers
Answer:
cant see it
Step-by-step explanation:
just type it out
On each trial of an experiment, a participant is presented with a constant soft noise, which is interrupted at some unpredictable time by a slightly louder sound. The time it takes for the participant to react to the louder sound is recorded. The following list contains the reaction times (in milliseconds) for trials of this experiment.
170, 206, 218, 232, 238, 248, 254, 264, 268, 281, 281, 281, 316, 320, 320, 329, 336, 365, 399, 400, 438, 438, 452, 524, 724, 806
1. measures of central tendency do not exist for this data set?
a. Mean
b. Median
c. Mode
d. None of these measures
2. Suppose that the measurement 806 (the largest measurement in the data set) were replaced by 1169. Which measures of central tendency would be affected by the change? Choose all that apply.
Answers
Answer:
1.d. None of these measures (do not exist interpreted as all of these exist)
2.The mean is increased from 346.8 to 361.32
Step-by-step explanation:
After calculations we find that all the measures of central tendency exist for this data. The mean , median and mode can be easily calculated .
The mean is 346.8
The mode is 281
The median is 316
Suppose that the measurement 806 (the largest measurement in the data set) were replaced by 1169. The mean would be affected by the change.
The mean is 361.32
The mode is 281
The median is 316
The mean is increased from 346.8 to 361.32
Your city has a sales tax rate of 6%. If you just spent $30 on sales tax, how much were your purchases?
Answers
Answer:
30.00×.06=1.8+30.00=31.8
The points A(-3, -4) and B(5, 0) form a line segment. Find the coordinates of the point P that partitions segment AB in a 2:3 ratio.
Answers
Answer:
Step-by-step explanation:
let the coordinates of P be (x,y)
[tex]x=\frac{mx2+nx1}{m+n} \\y=\frac{my2+ny1}{m+n} \\x=\frac{2(5)+3(-3)}{2+3} \\x=\frac{10-9}{5} =\frac{1}{5} =0.2\\y=\frac{2(0)+3(-4)}{2+3} \\y=\frac{0-12}{5} =\frac{-12}{5} =-2.4\\[/tex]
so coordinates of P are (0.2,-2.4)
How many different committees can be formed from 6 teachers and 37 students if the committee consists of 4 teachers and 4 students?
The committee of 8 members can be selected in
BLANK different ways.
Answers
Answer:
The committee of 8 members can be selected in 990,675 different ways.
Step-by-step explanation:
The order in which the teachers and the students are chosen is not important, which means that the combinations formula is used to solve this question.
Combinations formula:
[tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
In this question:
4 teachers from a set of 6.
4 students from a set of 37.
Then
[tex]T = C_{6,4}C_{37,4} = \frac{6!}{4!2!} \times \frac{37!}{4!33!} = 990675[/tex]
The committee of 8 members can be selected in 990,675 different ways.
find the area of the given figure
Answers
[tex]\sf \bf {\boxed {\mathbb {GIVEN:}}}[/tex]
Radius of the circle "[tex]r[/tex]" = 5.5 yd
[tex]\sf \bf {\boxed {\mathbb {TO\:FIND:}}}[/tex]
The area of the given figure.
[tex]\sf \bf {\boxed {\mathbb {SOLUTION :}}}[/tex]
[tex]\implies {\blue {\boxed {\boxed {\purple {\sf {b. \:47.5\:sq\:yd.}}}}}}[/tex]
[tex]\sf \bf {\boxed {\mathbb {STEP-BY-STEP\:EXPLANATION:}}}[/tex]
We know that,
[tex]\sf\pink{Area\:of\:a\:semi-circle}[/tex] = [tex]\frac{\pi \: {r}^{2} }{2} [/tex]
Using 3.14 for π, we have
[tex] = \frac{3.14 \times ( {5.5 \: yd})^{2} }{2} \\[/tex]
[tex] = \frac{3.14 \times 5.5 \times 5.5 \: {yd}^{2} }{2}\\ [/tex]
[tex] = \frac{94.985 \: {yd}^{2} }{2} \\[/tex]
[tex] = 47.5 \: {yd}^{2} \\[/tex]
Using [tex]\frac{22}{7} [/tex] for π,
[tex] = \frac{22 \times 5.5 \times 5.5 \: {yd}^{2} }{7 \times 2} \\[/tex]
[tex] = \frac{665.5 \: {yd}^{2} }{14}\\ [/tex]
[tex] = 47.5 \: {yd}^{2} \\[/tex]
Therefore, the area of the semi-circle is [tex]47.5\: yd²[/tex].
[tex]\huge{\textbf{\textsf{{\orange{My}}{\blue{st}}{\pink{iq}}{\purple{ue}}{\red{35}}{\green{♨}}}}}[/tex]
please answer i will mark brainliest :)
Answers
Answer:
c I think that's the right answer
If the circumference of the circle is 88 cm, then its radius is 14 cm.
true or false?
Answers
Answer:
The radius is approximately 14 cm
Step-by-step explanation:
The circumference
C = 2 * pi *r
88 = 2 * pi *r
Divide by 2
44 = 3.14 *r
Divide by 3.14
44/3.14 = r
14.01273885=r
88/2= 44
