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Arturiano [62]
1 year ago
9

Alejandro wants to determine the average shoe size of all of the male students in his school. Which sample is likely to yield th

e most biased results? A.every tenth boy on the school’s phone list B.every member of the boys’ basketball team C.every boy in a randomly selected ninth-, tenth-, eleventh-, and twelfth-grade gym class D.every fifth boy who walks through the front doors of the school in the morning
Mathematics
2 answers:
Dimas [21]1 year ago
5 0
B. every member of the boys' basketball team 

because people who play basketball are generally taller which means they have bigger feet (most of the time) which doesn't accurately represent the average of the male student body. 
larisa86 [58]1 year ago
5 0
<h2>Answer:</h2>

Option: B is the correct answer.

B.   Every member of the boys’ basketball team

<h2>Step-by-step explanation:</h2>

We know that a biased sample is one in which the sample is not random.

There is some partiality or some preference of choosing a member of a sample.

A.) Every tenth boy on the school’s phone list.

As the choosing of the members of a sample is random i.e. each student has an equal probability of getting chosen.

             Hence, the sample is not biased.

C.)  Every boy in a randomly selected ninth-, tenth-, eleventh-, and twelfth-grade gym class.

Again this sample is random.

                     Hence, the option is incorrect.

D.) Every fifth boy who walks through the front doors of the school in the morning.

In this sample every person has an equal probability.

           Hence, the sample is not biased.

B.)  Every member of the boys’ basketball team.

This is a biased sample since the members in the basketball team have a big height and hence their foot size is also big. So, we can't obtain a good result for determining the average shoe size of all the male students in the school.

                  Hence, the sample is biased.

You might be interested in
 if xy=c^2, prove that x^2 dx/dy+c^2=0
tatyana61 [14]
Hello,

xy=c²==>y=c²/x
==>y'=dy/dx=-c²/x²==>x² dy/dx+c²=0 (there is a mistake)

7 0
1 year ago
Suppose that in one region of the country the mean amount of credit card debt perhousehold in households having credit card debt
kvv77 [185]

Answer:

The probability that the mean amount of credit card debt in a sample of 1600 such households will be within $300 of the population mean is roughly 0.907 = 90.7%.

Step-by-step explanation:

To solve this question, we have to understand the normal probability distribution and the central limit theorem.

Normal probability distribution:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central limit theorem:

The Central Limit Theorem estabilishes that, for a random variable X, with mean \mu and standard deviation \sigma, a large sample size can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}

In this problem, we have that:

\mu = 15250, \sigma = 7125, n = 1600, s = \frac{7125}{\sqrt{1600}} = 178.125

The probability that the mean amount of credit card debt in a sample of 1600 such households will be within $300 of the population mean is roughly

This probability is the pvalue of Z when X = 1600 + 300 = 1900 subtracted by the pvalue of Z when X = 1600 - 300 = 1300. So

X = 1900

Z = \frac{X - \mu}{\sigma}

By the Central Limit Theorem

Z = \frac{X - \mu}{s}

Z = \frac{1900 - 1600}{178.125}

Z = 1.68

Z = 1.68 has a pvalue of 0.9535.

X = 1300

Z = \frac{X - \mu}{s}

Z = \frac{1300 - 1600}{178.125}

Z = -1.68

Z = -1.68 has a pvalue of 0.0465.

0.9535 - 0.0465 = 0.907.

The probability that the mean amount of credit card debt in a sample of 1600 such households will be within $300 of the population mean is roughly 0.907 = 90.7%.

7 0
2 years ago
The base of the isosceles triangle is parallel to x-axis and has both end-points on the parabola y=x(10−x) and its vertex belong
baherus [9]

Answer:

36

Step-by-step explanation:

We must determine the x and y intercepts of the parabola:

When y=0, x=0 or x=10

WE know that the point of the triangle base is x and x+8. We can substitute this into the parabola equation because the endpoints are on the parabola.

f(x+8)=-(x^2+16x+64)+10x+80

f(x+8)=-x^2-6x+16

f(x)=f(x+8)

-x^2+10x=-x^2-6x+16

solve for x

16x=16

x=1

Therefore the heigh is f(1):

=-1^2+10=9

The area of the triangle is 1/2 base x height:

=(1/2)\cdot{8}\cdot{9}=36

6 0
2 years ago
Two random samples are taken from private and public universities
kati45 [8]

Answer:

Step-by-step explanation:

For private Institutions,

n = 20

Mean, x1 = (43120 + 28190 + 34490 + 20893 + 42984 + 34750 + 44897 + 32198 + 18432 + 33981 + 29498 + 31980 + 22764 + 54190 + 37756 + 30129 + 33980 + 47909 + 32200 + 38120)/20 = 34623.05

Standard deviation = √(summation(x - mean)²/n

Summation(x - mean)² = (43120 - 34623.05)^2+ (28190 - 34623.05)^2 + (34490 - 34623.05)^2 + (20893 - 34623.05)^2 + (42984 - 34623.05)^2 + (34750 - 34623.05)^2 + (44897 - 34623.05)^2 + (32198 - 34623.05)^2 + (18432 - 34623.05)^2 + (33981 - 34623.05)^2 + (29498 - 34623.05)^2 + (31980 - 34623.05)^2 + (22764 - 34623.05)^2 + (54190 - 34623.05)^2 + (37756 - 34623.05)^2 + (30129 - 34623.05)^2 + (33980 - 34623.05)^2 + (47909 - 34623.05)^2 + (32200 - 34623.05)^2 + (38120 - 34623.05)^2 = 1527829234.95

Standard deviation = √(1527829234.95/20

s1 = 8740.22

For public Institutions,

n = 20

Mean, x2 = (25469 + 19450 + 18347 + 28560 + 32592 + 21871 + 24120 + 27450 + 29100 + 21870 + 22650 + 29143 + 25379 + 23450 + 23871 + 28745 + 30120 + 21190 + 21540 + 26346)/20 = 25063.15

Summation(x - mean)² = (25469 - 25063.15)^2+ (19450 - 25063.15)^2 + (18347 - 25063.15)^2 + (28560 - 25063.15)^2 + (32592 - 25063.15)^2 + (21871 - 25063.15)^2 + (24120 - 25063.15)^2 + (27450 - 25063.15)^2 + (29100 - 25063.15)^2 + (21870 - 25063.15)^2 + (22650 - 25063.15)^2 + (29143 - 25063.15)^2 + (25379 - 25063.15)^2 + (23450 - 25063.15)^2 + (23871 - 25063.15)^2 + (28745 - 25063.15)^2 + (30120 - 25063.15)^2 + (21190 - 25063.15)^2 + (21540 - 25063.15)^2 + (26346 - 25063.15)^2 = 1527829234.95

Standard deviation = √(283738188.55/20

s2 = 3766.55

This is a test of 2 independent groups. Let μ1 be the mean out-of-state tuition for private institutions and μ2 be the mean out-of-state tuition for public institutions.

The random variable is μ1 - μ2 = difference in the mean out-of-state tuition for private institutions and the mean out-of-state tuition for public institutions.

We would set up the hypothesis. The correct option is

-B. H0: μ1 = μ2 ; H1: μ1 > μ2

Since sample standard deviation is known, we would determine the test statistic by using the t test. The formula is

(x1 - x2)/√(s1²/n1 + s2²/n2)

t = (34623.05 - 25063.15)/√(8740.22²/20 + 3766.55²/20)

t = 9559.9/2128.12528473889

t = 4.49

The formula for determining the degree of freedom is

df = [s1²/n1 + s2²/n2]²/(1/n1 - 1)(s1²/n1)² + (1/n2 - 1)(s2²/n2)²

df = [8740.22²/20 + 3766.55²/20]²/[(1/20 - 1)(8740.22²/20)² + (1/20 - 1)(3766.55²/20)²] = 20511091253953.727/794331719568.7114

df = 26

We would determine the probability value from the t test calculator. It becomes

p value = 0.000065

Since alpha, 0.01 > than the p value, 0.000065, then we would reject the null hypothesis. Therefore, at 1% significance level, the mean out-of-state tuition for private institutions is statistically significantly higher than public institutions.

4 0
1 year ago
Which real-world scenario can be described by the algebraic expression 4w? withdrawing w dollars from the bank and giving 4 doll
ANTONII [103]

Answer:

It's B

Step-by-step explanation:

3 0
1 year ago
Read 2 more answers
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