Answer:
Sara studies longer by 15 minutes.
Step-by-step explanation:
Let's calculate how long Sebastian studies for. From 3:15 - 4:15, there is 1 hour and from 4:15 to 4:45, there are 30 minutes so Sebastian studies for 1 hour and 30 minutes. Now, let's calculate how long Sara studies for. From 4:30 - 5:30, there is 1 hour, from 5:30 - 6:00, there are 30 minutes and from 6:00 - 6:15, there are 15 minutes so Sara studies for 1 hour 45 minutes. This means that Sara studies longer by 45 - 30 = 15 minutes.
Find three different numbers such that the
HCF of each pair of these numbers is greater
than 1 but the HCF of all three numbers is 1.
[Hint: For instance, the numbers 6, 10 and
15 satisfy the conditions.]
6, 10, 15
15,21,35
35, 55, 77
77, 91, 143
143, 187, 221
I can go on forever
There are different possibilities
The video indicates which of the following is an acceptable alternative to washing your hands for 20 seconds with respect to preventing illness? getting a flu shot using hand sanitizer with at least 60% alcohol rinsing with mouthwash that has at least 15% alcohol washing your hands for 10 seconds with water that exceeds 100 degrees Fahrenheit The video urges people to wash their hands to reduce the likelihood (that is, the probability) of contracting diseases. What does this imply? The probability of contracting a disease is lower if you wash your hands than if you don't wash your hands. That is: P(disease if you wash your hands) < P(disease if you don't wash your hands). If you don't wash your hands, you will contract a disease. That is: P(contracting a disease if you don't wash your hands) = 1. If you contracted a disease, you must have not washed your hands. That is: P(washed your hands if you contracted a disease) = 0. If you wash your hands, you will not contract a disease. That is: P(contracting a disease if you wash your hands) = 0. Suppose a student has had one illness in the last month, b
Answer:
1. using hand sanitizer with at least 60% alcohol
2. the probability of contracting a disease is lower if you wash your hands than if you don't wash your hands. That is: P (disease if you wash your hands) < P (disease if you don't wash your hands).
Step-by-step explanation:
1. Noteworthy is the fact that alcohol based hand sanitizers provide good protections to germs, viruses as when one washes his hands with soap for 20 seconds. This was indicated in the video as an acceptable alternative to washing your hands for 20 seconds with respect to preventing illness.
2. Remember, probability implies an assumption of possiblity or likelihood of something happening. Thus, the video's message implies that when people wash their hands it reduces the likelihood (that is, the probability) of contracting diseases. One stands a lower chance of : P (disease if you wash your hands) < P (disease if you don't wash your hands).
James has a total of 66 dollars in his piggy bank. He only has one dollar bills and two dollar bills in his piggy bank. If there are a total of 49 bills in James's piggy bank, how many one dollar bills does he have?
Answer:
32 one-dollar bills.
Step-by-step explanation:
Let x represent one-dollar bills and y represent two-dollar bills.
He has a total of 49 bills. Therefore:
[tex]x+y=49[/tex]
The total amount of money James has is 66. x is worth one dollar, while y is worth two dollars. Therefore:
[tex]1x+2y=66\\x+2y=66[/tex]
We have a system of equations. Solve by substitution:
[tex]x+2y=66\\x+y=49\\x=49-y\\(49-y)+2y=66\\y=17\\x=49-17=32[/tex]
Therefore, James has 32 one-dollar bills and 17 two-dollar bills.
Checking:
[tex]32(1)+17(2)\stackrel{?}{=}66\\32(1)+17(2)\stackrel{\checkmark}{=}66\\\\32+17\stackrel{?}{=}49\\49\stackrel{\checkmark}{=}49[/tex]
What inequality does this number line show?
Let X denote the day she gets enrolled in her first class and let Y denote the day she gets enrolled in both the classes. What is the distribution of X
Answer:
X is uniformly distributed.
Step-by-step explanation:
Uniform Distribution:
This is the type of distribution where all outcome of a certain event have equal likeliness of occurrence.
Example of Uniform Distribution is - tossing a coin. The probability of getting a head is the same as the probability of getting a tail. The have equal likeliness of occurrence.
Is -5/6 Real, Rational, Irrational, Integer, Whole, or real number?
Answer:
Rational
Step-by-step explanation:
Rational number consists of
Whole NumbersNatural NumbersIntegersNegative NumbersFractionsDecimals-5/6 is a Fraction and we can also simply it to a Decimal.
Hope this helps ;) ❤❤❤
Can the sides of a triangle be in the given ratio? 3:4:5
Answer:
Yes
Step-by-step explanation:
Yes, and it’s a right triangle.
3²+4²=5²
9+16=25
25=25
Answer:
Yes
Step-by-step explanation:
In order to determine if a triple of values will form a triangle, we must apply the Triangle Inequality Theorem, which states that for a triangle with lengths a, b, and c:
a + b > c
a + c > b
b + c > a
Here, let's suppose that since the ratio of the sides is 3 : 4 : 5, then let the actual side lengths be 3x, 4x, and 5x, where x is simply a real value.
With loss of generality, set a = 3x, b = 4x, and c = 5x. Plug these into the Triangle Inequality to check:
a + b > c ⇒ 3x + 4x >? 5x ⇒ 7x > 5x ⇒ This is true
a + c > b ⇒ 3x + 5x >? 4x ⇒ 8x > 4x ⇒ This is also true
b + c > a ⇒ 4x + 5x >? 3x ⇒ 9x > 3x ⇒ This is true
Since all three conditions are satisfied, we know that a true triangle can be formed given that the ratio of their sides is 3 : 4 : 5.
~ an aesthetics lover
12-(3-9) 3*3 help please
Step-by-step explanation:
42 is your answer according to bodmas
A thin metal plate, located in the xy-plane, has temperature T(x, y) at the point (x, y). Sketch some level curves (isothermals) if the temperature function is given by
T(x, y)= 100/1+x^2+2y^2
Answer:
Step-by-step explanation:
Given that:
[tex]T(x,y) = \dfrac{100}{1+x^2+y^2}[/tex]
This implies that the level curves of a function(f) of two variables relates with the curves with equation f(x,y) = c
here c is the constant.
[tex]c = \dfrac{100}{1+x^2+2y^2} \ \ \--- (1)[/tex]
By cross multiply
[tex]c({1+x^2+2y^2}) = 100[/tex]
[tex]1+x^2+2y^2 = \dfrac{100}{c}[/tex]
[tex]x^2+2y^2 = \dfrac{100}{c} - 1 \ \ -- (2)[/tex]
From (2); let assume that the values of c > 0 likewise c < 100, then the interval can be expressed as 0 < c <100.
Now,
[tex]\dfrac{(x)^2}{\dfrac{100}{c}-1 } + \dfrac{(y)^2}{\dfrac{50}{c}-\dfrac{1}{2} }=1[/tex]
This is the equation for the family of the eclipses centred at (0,0) is :
[tex]\dfrac{x^2}{a^2}+\dfrac{y^2}{b^2}=1[/tex]
[tex]a^2 = \dfrac{100}{c} -1 \ \ and \ \ b^2 = \dfrac{50}{c}- \dfrac{1}{2}[/tex]
Therefore; the level of the curves are all the eclipses with the major axis:
[tex]a = \sqrt{\dfrac{100 }{c}-1}[/tex] and a minor axis [tex]b = \sqrt{\dfrac{50 }{c}-\dfrac{1}{2}}[/tex] which satisfies the values for which 0< c < 100.
The sketch of the level curves can be see in the attached image below.
10
[tex] {10}^{4} = [/tex]
whats the answer..
Answer:
10,000
Step-by-step explanation:
The answer is 10*10*10*10 = 10,000
When the power is positive and in the numerator, the number of places moved or zeros added = the power. This has a power of 4. You add 4 zeros to 1 to get the answer.
Find an equation of the tangent to the curve at the given point by both eliminating the parameter and without eliminating the parameter. x = 5 + ln(t), y = t2 + 2, (5, 3)
Answer:
Step-by-step explanation:
Given that:
[tex]x = 5 + In (t)[/tex]
[tex]y = t^2+2[/tex]
At point (5,3)
To find an equation of the tangent to the curve at the given point,
By without eliminating the parameter
[tex]\dfrac{dx}{dt}= \dfrac{1}{t}[/tex]
[tex]\dfrac{dy}{dt}= 2t[/tex]
[tex]\dfrac{dy}{dx}= \dfrac{ \dfrac{dy}{dt} }{\dfrac{dx}{dt} }[/tex]
[tex]\dfrac{dy}{dx}= \dfrac{ 2t }{\dfrac{1}{t} }[/tex]
[tex]\dfrac{dy}{dx}= 2t^2[/tex]
[tex]\dfrac{dy}{dx}_{ (5,3)}= 2t^2_{ (5,3)}[/tex]
t² + 5 = 4
t² = 4 - 5
t² = - 1
Then;
[tex]\dfrac{dy}{dx}_{ (5,3)}= -2[/tex]
The equation of the tangent is:
[tex]y -y_1 = m(x-x_1)[/tex]
[tex](y-3 )= -2(x - 5)[/tex]
y - 3 = -2x +10
y = -2x + 7
y = 2x - 7
By eliminating the parameter
x = 5 + In(t)
In(t) = 5 - x
[tex]t =e^{x-5}[/tex]
[tex]y = (e^{x-5})^2+5[/tex][tex]y = (e^{2x-10})+5[/tex]
[tex]\dfrac{dy}{dx} = 2e^{2x-10}[/tex]
[tex]\dfrac{dy}{dx}_{(5,3)} = 2e^{10-10}[/tex]
[tex]\dfrac{dy}{dx}_{(5,3)} = 2[/tex]
The equation of the tangent is:
[tex]y -y_1 = m(x-x_1)[/tex]
[tex](y-3 )= -2(x - 5)[/tex]
y - 3 = -2x +10
y = -2x + 7
y = 2x - 7
Bianca took a job that paid $150 the first week. She was guaranteed a raise of 6% each week. How much money will she make in all over 8 weeks? Round the answer to the nearest cent. please answer with the reasoning, I want to learn how to solve this and not just get the answer. Thank you.
Answer:
$225.54 (hope it help)
Step-by-step explanation:
for 2nd week
$150 for the first week and a raise of 6% each week
which means 150+6%
6% of 150 is 9 (150x0.06)
150+9=159
and it repeats
for 3rd week
6% of 159 is 9.54 (159x0.06)
159+9.54=168.54
for 4th week
6% of 168.54 is 10.1124 (168.54x0.06)
168.54+10.1124=178.652
for 5th week
6% of 178.652 is 10.71912 (178.652x0.06)
178.652+10.71912=189.37112
an easier to do it is to just do 178.652 + 6% on your calculater
and I'll skip all the way to the 8th since you know the formula
212.777390432+6%=225.544033858
225.544033858≈225.54
Choose the best answer to the following question. Explain your reasoning with one or more complete sentences. At 11:00 you place a single bacterium in a bottle, and at 11:01 it divides into 2 bacteria, which at 11:02 divide into 4 bacteria, and so on. How many bacteria will be in the bottle at 11:30?
Answer:
we could work this out by geometric sequence
Step-by-step explanation:
G1=2, G2=4, we have a formula,Gn=G1r^n-1
G2=G1 (r)^1, 4=2r, r=2
G30=G1 (2)^29=1,073,741,824 bacterium
How many 4 digit palidromes are there?
Which expression simplifies to 7W+5?
. – 2w + 3 + 5W – 2
C. -3w + 5(2W + 1)
Cual es la respuesta
Answer:
[tex]\large \boxed{\mathrm{-3w + 5(2w + 1)}}[/tex]
Step-by-step explanation:
-2w + 3 + 5w - 2
Combine like terms.
3w + 1
-3w + 5(2w + 1)
Expand brackets.
-3w + 10w + 5
Combine like terms.
7w + 5
Answer:
The answer is C.
-3w +5(2w +1)
Step-by-step explanation:
Findℒ{f(t)}by first using a trigonometric identity. (Write your answer as a function of s.)f(t) = 12 cost −π6
Answer:
[tex]L(f(t)) = \dfrac{6}{S^2+1} [\sqrt{3} \ S +1 ][/tex]
Step-by-step explanation:
Given that:
[tex]f(t) = 12 cos (t- \dfrac{\pi}{6})[/tex]
recall that:
cos (A-B) = cos AcosB + sin A sin B
∴
[tex]f(t) = 12 [cos\ t \ cos \dfrac{\pi}{6}+ sin \ t \ sin \dfrac{\pi}{6}][/tex]
[tex]f(t) = 12 [cos \ t \ \dfrac{3}{2}+ sin \ t \ sin \dfrac{1}{2}][/tex]
[tex]f(t) = 6 \sqrt{3} \ cos \ (t) + 6 \ sin \ (t)[/tex]
[tex]L(f(t)) = L ( 6 \sqrt{3} \ cos \ (t) + 6 \ sin \ (t) ][/tex]
[tex]L(f(t)) = 6 \sqrt{3} \ L [cos \ (t) ] + 6\ L [ sin \ (t) ][/tex]
[tex]L(f(t)) = 6 \sqrt{3} \dfrac{S}{S^2 + 1^2}+ 6 \dfrac{1}{S^2 +1^2}[/tex]
[tex]L(f(t)) = \dfrac{6 \sqrt{3} +6 }{S^2+1}[/tex]
[tex]L(f(t)) = \dfrac{6( \sqrt{3} \ S +1 }{S^2+1}[/tex]
[tex]L(f(t)) = \dfrac{6}{S^2+1} [\sqrt{3} \ S +1 ][/tex]
1. Peyton has a credit card with an annual rate of 24.7% compounded monthly. She used the credit card to purchase cleaning supplies in the amount of $189.56. She can pay up to $72 on the
credit card each month. How much total interest will she pay?
Answer:
Total interest = $3.41
Step-by-step explanation:
Since she can pay $72 each month we can divide the payments on monthly basis till all the money is paid.
The annual interest rate is 24.7%, so the monthly rate will be 24.7 ÷ 12= 2.058%
For the first month
With payment of $72 the remaining amount will be 189.56 - 72 = $117.56
Interest paid will be 0.02058 * 117.56 = $2.42
Total amount owed now will be 117.56 + 2.42 = $119.98
For the second month another payment of $72 is made
The remaining will be 119.98 - 72 = $47.98
Interest charged will be 0.02058 * 47.98 = $0.99
The amount owed will be 47.98 + 0.99 = $48.97
In the third month she will pay the remaining $47.98 which is within her monthly limit
Total interest paid = Sum of Amount paid each month - Initial amount spent
Total interest = {(72 * 2) +48.97} - 189.56 = $3.41
The numerator of a fraction is 8 less than the denominator of a fraction. The value of the fraction is 3/5, find the value of the fraction.
Hello!
Answer:
[tex]\huge\boxed{\frac{12}{20}}[/tex]
To find the numerator and denominator, we can set up a proportion where:
x = denominator
x -8 = numerator
[tex]\frac{3}{5} = \frac{x-8}{x}[/tex]
Cross multiply:
[tex]3(x) = 5(x - 8)[/tex]
[tex]3x = 5x - 40[/tex]
Simplify:
[tex]3x - 5x = -40\\\\-2x = -40\\\\x = 20[/tex]
Substitute in this value of x to find the numerator and denominator:
[tex]\frac{(20) - 8}{(20)} = \frac{12}{20}[/tex]
Hope this helped you! :)
[tex] \LARGE{ \boxed{ \rm{ \orange{ Solution:}}}}[/tex]
Let the numerator be x
It is given that,
Denominator - 8 = NumeratorThen,
⇛ Denominator- 8 = x
⇛ Denominator = x + 8
According to condition -2)
⇛ Fraction = 3/5
⇛ x/x + 8 = 3/5
Cross multiplying,
⇛ 3(x + 8) = 5x
⇛ 3x + 24 = 5x
⇛ 24 = 5x - 3x
⇛ 24 = 24
Flipping it out,
⇛ 2x = 24
⇛ x = 24/2 = 12
Then,
⇛ x + 8 = 12 + 8 = 20
Numerator = 12Denominator = 20[tex] \large{ \therefore{ \boxed{ \rm{ \pink{Then, \: the \: fraction = \dfrac{12}{20} }}}}}[/tex]
━━━━━━━━━━━━━━━━━━━━
Suppose _ . Compute the following:
Step-by-step explanation:
f(x) = x² - 5x - 9
To solve both expressions first find f( -4) and f(5)
For f(- 4)
Substitute the value of x that's - 4 into the expression
That's
f(-4) = (-4)² - 5(-4) - 9
= 16 + 20 - 9
= 36 - 9
f(-4) = 27For f(-5)
Substitute 5 into f (x)
That's
f(5) = 5² - 5(5) - 9
= 25 - 25 - 9
f(5) = - 9A).f(-4) + f(5) = 27 - 9 = 18B). f(-4) - f(5) = 27 -- 9 = 27 + 9 = 36Hope this helps you
Please help! Make sure to simplify
[tex] \frac{5b^{5}c}{4c^4} \times \frac{8c}{b^4}[/tex]
[tex]\frac{40b^{5}c^2}{4b^{4}c^4}[/tex]
[tex]{10b^{5-4}c^{2-4}}[/tex]
[tex]10bc^-2[/tex]
[tex]\frac{10b}{c^2}[/tex]
Step-by-step explanation:
[tex] \frac{5 {b}^{5} c}{ 4{c}^{4} } \times \frac{8c}{ {b}^{4} } [/tex]
First reduce the expression with b⁴
b⁴ will cancel b^5 remaining with one b
That's
[tex] \frac{5bc}{4 {c}^{4} } \times 8c[/tex]Next reduce 8 and 4 with their GCF which is 4
We have
[tex] \frac{5bc}{ {c}^{4} } \times 2c[/tex]Reduce the expression with c .
c will go into c⁴ remaining with c³
That's
[tex] \frac{5bc}{ {c}^{3} } \times 2[/tex]Simplify the expression again with c
That's
[tex] \frac{5b}{ {c}^{2} } \times 2[/tex]Multiply the expression
We have the final answer as
[tex] \frac{10b}{ {c}^{2} } [/tex]Hope this helps you
can you please help me with this
Answer:
[tex]\displaystyle A=\dfrac{1}{2}\int_\pi^{\frac{7\pi}{6}}{(\cos{\theta}+\sin{2\theta})^2}\,d\theta[/tex]
Step-by-step explanation:
The shaded area is the area of the curve bounded by θ = π and θ = 7π/6.* A differential of area in polar coordinates is ...
dA = (1/2)r^2·dθ
So, the shaded area is ...
[tex]\displaystyle\boxed{A=\dfrac{1}{2}\int_\pi^{\frac{7\pi}{6}}{(\cos{\theta}+\sin{2\theta})^2}\,d\theta}[/tex]
_____
* We found these bounds by trial and error using a graphing calculator to plot portions of the curve.
Write three fractions that are equivalent to 3 over 11 , but written in higher terms. One of them must
include one or more variables.
Answer:
Three fractions that are equivalent to [tex]\frac{3}{11}[/tex] are: [tex]\frac{6}{22}[/tex], [tex]\frac{24}{88}[/tex] and [tex]\frac{144}{528}[/tex].
Step-by-step explanation:
Equivalent fractions are set of fractions in which when simplified, they have the same answer.
Given: [tex]\frac{3}{11}[/tex]
i. multiply the numerator and denominator of [tex]\frac{3}{11}[/tex] by 2,
= [tex]\frac{3*2}{11*2}[/tex] = [tex]\frac{6}{22}[/tex]
i. multiply both the numerator and denominator of [tex]\frac{6}{22}[/tex] by 4,
= [tex]\frac{6*4}{22*4}[/tex]= [tex]\frac{24}{88}[/tex]
ii. multiply the numerator and denominator of [tex]\frac{24}{88}[/tex] by 6,
= [tex]\frac{24*6}{88*6}[/tex] = [tex]\frac{144}{528}[/tex]
So that;
[tex]\frac{3}{11}[/tex] = [tex]\frac{6}{22}[/tex] = [tex]\frac{24}{88}[/tex] = [tex]\frac{144}{528}[/tex].
Three fractions that are equivalent to [tex]\frac{3}{11}[/tex] are: [tex]\frac{6}{22}[/tex], [tex]\frac{24}{88}[/tex] and [tex]\frac{144}{528}[/tex].
Write
801
1000
as a decimal number.
Answer:
0.801
Step-by-step explanation:
Answer:
0.801
Step-by-step explanation:
801/1000 = 0.801
50. Carrie is running for mayor in her local city election. In order to win, she must earn over 50% of the votes. ecides to hire a couple of Statistics students to help her measure the progress in her campaign through polling. She is hoping to find sufficient evidence (a=0.05) that she will in fact win the election with more than 50% of the vote. The Statistics students test the following hypotheses, where p represents the proportion of all voters who will vote for Jemmy. which of the following statements would be true if a Type I error is made? (Select all that apply.)
a. Carrie ends up winning the election.
b. The students find a p-value less than 0.05 .
c. Carrie ends up losing the election.
d. The students find a p-value greater than 0.05
e. The students make the conclusion that Carrie does not have more than 50% of the vote.
f. The students make the conclusion that Carrie will have more than 50% of the vote. e.
Answer:
b. The students find a p-value less than 0.05
c. Carrie ends up losing the election.
e. The students make the conclusion that Carrie does not have more than 50% of the vote.
Step-by-step explanation:
Null hypothesis is a statement that is to be tested against the alternative hypothesis and then decision is taken whether to accept or reject the null hypothesis.
Type I error is one in which we reject a true null hypothesis.
In the given scenario Type I error will be the one where students incorrectly estimates the p value and reject the null hypothesis when it was true. This error will result in losing the elections.
4 + (-13)
Yajmmsmssjsjsjjsnssnsnnsnsxxdddddddd
Answer:
-9
Step-by-step explanation:
4 + (-13)
=> 4 - 13
=> -9
15+9=? (5+3) What number is missing from the expression?
Answer:
[tex] \boxed{ \boxed{ \bold{ \mathsf{3}}}}[/tex]Step-by-step explanation:
Let the missing number be 'x'
⇒[tex] \mathsf{15 + 9 = x(5 + 3)}[/tex]
Distribute x through the parentheses
⇒[tex] \mathsf{15 + 9 = 5x + 3x}[/tex]
Swap the sides of the equation
⇒[tex] \mathsf{5x + 3x = 15 + 9}[/tex]
Add the numbers
⇒[tex] \mathsf{5x + 3x = 24}[/tex]
Collect like terms
⇒[tex] \mathsf{8x = 24}[/tex]
Divide both sides of the equation by 8
⇒[tex] \mathsf{ \frac{8x}{8} = \frac{24}{8} }[/tex]
Calculate
⇒[tex] \mathsf{x = 3}[/tex]
Hope I helped!
Best regards!
Laura is bowling 5 games. Her first 4 scores were 135, 144, 116, and 132.
To end up with an average score of at least 136.8, what is the lowest score Laura will need in the fifth game?
Answer:
it doesnt add up. the question doesnt make sense.
Step-by-step explanation:
Answer:
157
Step-by-step explanation:
To find the average score, add all individual scores and divide the sum by the number of individual scores.
She has 5 individual scores. Let's say her scores are A, B, C, D, and E.
average score = (A + B + C + D + E)/5
Now we plug in the average and the 4 known scores for A through D, and we solve for E.
average score = (A + B + C + D + E)/5
136.8 = (135 + 144 + 116 + 132 + E)/5
E = 157
Answer: 157
Let f(x) = 8x3 + 16x2 − 15 and g(x) = 2x + 1. Find f of x over g of x
[tex]\dfrac{f(x)}{g(x)}=\dfrac{8x^3+16x^2-15}{2x+1}[/tex]
Solve 13x + 14 = 12x -5 (make sure to type the number only)
Answer:
x = -19
Step-by-step explanation:
13x + 14 = 12x - 5
subtract 12x from both sides
x + 14 = -5
subtract 14 from both sides
x = -19
Answer:
x= -19
Step-by-step explanation:
13x+14=12x−5
Subtract 12x from both sides.
13x+14−12x=−5
Combine 13x and −12x to get x.
x+14=−5
Subtract 14 from both sides.
x=−5−14
Subtract 14 from −5 to get −19
x=−19
To determine her water pressure, Denise divides up her day into three parts: morning, afternoon, and evening. She then measures her water pressure at 2 randomly selected times during each part of the day.What type of sampling is used?a. Simple random b. Cluster c. Stratified d. Convenience e. Systematic
Answer:
The correct answer is:
Stratified (c.)
Step-by-step explanation:
Stratified sampling technique is one in which the groups of data are divided into smaller groups or strata, based on shared common characteristics in these groups, and the samples randomly selected from each group in a proportional way. In this example, the sub-groups used is "times of the day" ie. morning, afternoon or evening. Other strata that can be used are; age, gender, continents etc. Stratification is done when the researcher wants to understand the relationships between the two or more groups. Stratified random sampling is also known as proportional random sampling or quota random sampling.
