Question

Determine if you are to use a normal distribution, a t-distribution, or a population proportion. Then, find the 95% confidence interval. a) In 34 randomly selected closing stock prices, the mean closing price was $19.96 and the population standard deviation was $2.62. Interval: b) In a random sample of 18 high school students, the mean hours spent on homework was 11.6 hours and the sample standard deviation was 3.04 hours. Interval: c) In a survey of 674 US males ages 18 to 64, 396 said that they have gone to the dentist in the past year. Interval:

Answer 1

Given Data: - 95% confidence Intoval: - a) n= 34 a $19.96 r = $2.62 i txtz, df - of - 34-1333 95%CI * = 5% -0.05 to-025, 33 = 2,0345 95% CI = ã I talp, at x 5 5 = 19.96 + 2.0345 x eo 19.046 ; 20.874 = 19.96 + 01914 95%CI -19.046 ; 20.874 b) n = 18 n 11.6 r=3.04 tal2, df = df = n-1 -18-1=17 to.025,19 = 2.10 95% CI = R I tolz, df xã = 1116 + 2.11 Xsa = 11.6 I 10512 = 10.088 ; 13.112 95% CI : 10.088; 13.112) c) x = 674 n= 64396 pa se on = 0.0105 Z412 • L-025 = ( 16. 95%C1 = P + Zarz PC-P) = 0.0105 I 1.96x f0:01061-0-405) -0.010576.96% locowe ks = 0.0105 +00008 = 0.0097 ; 0.0113 1 95CI = 0.0097 ; 0.0113) ✓ Guam = 0.010511696 70.000000 16 64396