Question

Based on a survey of 130 AUS students, we found 36 of them are using iPhone. Do we have enough evidence to conclude that about 30% of AUS students are using iPhone at 15% level of significance?

Answer 1

At 15% level of significance implies an 85% confidence level. We create a 85% Confidence interval

85% CI=$\hat p±z^* \sqrt{\frac{\hat p(1- \hat p)}{n}}$

$\hat p=\frac {36}{130}=0.2769$

=$0.2769±1.44\sqrt{\frac{0.2769(1-0.2769)}{130}}$

=(0. 2204, 0.3334)

Since 0.3 is within the range, we can conclude that about 30%of AUS students are using iPhone at 15 %level of significance.