1. In a survey, 600 mothers and fathers were asked about the importance of sport

Question

1. In a survey, 600 mothers and fathers were asked about the importance of sports for boys and girls. Of the parents interviewed, 70% said the genders are equal and should have equal opportunities to participate in sports.

A. What are the mean, standard deviation, and shape of the distribution of the sample proportion p ˆ of parents who say the genders are equal and should have equal opportunities? Be sure to justify your answer for the shape of the distribution. Use n = 600.

mean=.7   

standard deviation= .0187

shape- bell-shaped, approx normal; meets all conditions, np>=10, nq>=10, 10n<=N

B. Using the normal approximation without the continuity correction, sketch the probability distribution curve for the distribution of p ˆ. Shade equal areas on both sides of the mean to show an area that represents a probability of .95, and label the upper and lower bounds of the shaded area as values of p-hat (not z-scores). Show your calculations for the upper and lower bounds.

.0187 * 1.962 + .7= .7366

.0187 * 1.962 - .7 = .6633

C. Considering the sketch in part B, the shaded area shows a .95 probability of what happening? In other words, what does the probability of .95 represent?

It shows a .95 probability of the mean of p-hat being between .6633 and .7366.

D. Using the normal approximation, what's the probability a randomly drawn sample of parents of size 600 will have a sample proportion between 67% and 73%? Draw a sketch of the probability curve, shade the area representing the probability you're finding, and label the z-scores that represent the upper and lower bounds of the probability you're finding. Don't use the continuity correction.

P (.67 < p-hat < .73)

z .67= -1.61--> .0537

z . 73= +1.61--> .9463

P = .8926

E. Now, use the exact binomial calculation to find the probability of getting between, but not including, 67% and 73% of the respondents in a sample of 600 who say the genders are equal and should have equal opportunities. To use the exact binomial, you'll need to convert the proportions to counts by multiplying each proportion by 600. ***

F. Now try it again, but this time find the probability of getting at least 67% but no more than 73%. Use the exact binomial calculation. ****

as you can see, i have completed a-d of the problem. i don't fully understand how to find the exact binomial calculation and the difference between <= (less than or equal to) and < (less than). i know you use binompdf( n, p, x ) on the TI-84 PLUS (the calculator i am using). i also know you use P (X=x) = [n over x] p^x q^n-x.

Explanation / Answer

the difference between <= and < is that when you use normal aprox. you will have the same value but if you use binomial calculation ( binomial distribution) you will find the value of <=

for example <= 4 you will find the probabilities of 0 ,1,2,3, and 4

bt if you need <4 you will find only 0,1,2 and 3

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