Answer:
1) We need a random sample. For this case we assume that the sample selected was obtained using the simple random sampling method.
2) We need to satisfy the following inequalities:
![n\hat p =25*0.52= 13 \geq 10](https://tex.z-dn.net/?f=%20n%5Chat%20p%20%3D25%2A0.52%3D%2013%20%5Cgeq%2010)
![n(1-\hat p) = 25*(1-0.52) =12 \geq 10](https://tex.z-dn.net/?f=%20n%281-%5Chat%20p%29%20%3D%2025%2A%281-0.52%29%20%3D12%20%5Cgeq%2010)
So then we satisfy this condition
3) 10% condition. For this case we assume that the random sample selected n represent less than 10% of the population size N . And for this case we can assume this condition.
So then since all the conditions are satisfied we can conclude that we can apply the normal approximation given by:
![p \sim N (\hat p, \sqrt{\frac{\hat p (1-\hat p)}{n}})](https://tex.z-dn.net/?f=%20p%20%5Csim%20N%20%28%5Chat%20p%2C%20%5Csqrt%7B%5Cfrac%7B%5Chat%20p%20%281-%5Chat%20p%29%7D%7Bn%7D%7D%29)
So then the answer for this case would be:
a. Yes.
Explanation:
For this case we assume that the question is: If in the experiment described we can use the normal approximation for the proportion of interest.
For this case we have a sample of n =25
And we are interested in the proportion of registered students that spend more than 20 minutes to get to school.
X = 13 represent the number of students in the sample selected that have a time more than 20 min.
And then the estimated proportion of interest would be:
![\hat p = \frac{X}{n}= \frac{13}{25}= 0.52](https://tex.z-dn.net/?f=%5Chat%20p%20%3D%20%5Cfrac%7BX%7D%7Bn%7D%3D%20%5Cfrac%7B13%7D%7B25%7D%3D%200.52)
And we want to check if we can use the normal approximation given by:
![p \sim N (\hat p, \sqrt{\frac{\hat p (1-\hat p)}{n}})](https://tex.z-dn.net/?f=%20p%20%5Csim%20N%20%28%5Chat%20p%2C%20%5Csqrt%7B%5Cfrac%7B%5Chat%20p%20%281-%5Chat%20p%29%7D%7Bn%7D%7D%29)
So in order to do this approximation we need to satisfy some conditions listed below:
1) We need a random sample. For this case we assume that the sample selected was obtained using the simple random sampling method.
2) We need to satisfy the following inequalities:
![n\hat p =25*0.52= 13 \geq 10](https://tex.z-dn.net/?f=%20n%5Chat%20p%20%3D25%2A0.52%3D%2013%20%5Cgeq%2010)
![n(1-\hat p) = 25*(1-0.52) =12 \geq 10](https://tex.z-dn.net/?f=%20n%281-%5Chat%20p%29%20%3D%2025%2A%281-0.52%29%20%3D12%20%5Cgeq%2010)
So then we satisfy this condition:
3) 10% condition. For this case we assume that the random sample selected n represent less than 10% of the population size N . And for this case we can assume this condition.
So then since all the conditions are satisfied we can conclude that we can apply the normal approximation given by:
![p \sim N (\hat p, \sqrt{\frac{\hat p (1-\hat p)}{n}})](https://tex.z-dn.net/?f=%20p%20%5Csim%20N%20%28%5Chat%20p%2C%20%5Csqrt%7B%5Cfrac%7B%5Chat%20p%20%281-%5Chat%20p%29%7D%7Bn%7D%7D%29)
So then the answer for this case would be:
a. Yes.