In: Statistics and Probability
3) In a survey of 517 music teachers, 403 said that the video games Guitar Hero and Rock Band have a positive effect on music education. Construct a 98% confidence interval for the proportion of music teachers who believe that these video games have a positive effect. Write a sentence that interprets this interval
Solution :
Given that,
n = 517
x = 403
Point estimate = sample proportion = = x / n = 403/517=0.779
1 - = 1- 0.779 =0.221
At 98% confidence level the z is ,
= 1 - 98% = 1 - 0.98 = 0.02
/ 2 = 0.02/ 2 = 0.01
Z/2 = Z0.01 = 2.326 ( Using z table )
Margin of error = E = Z / 2 *( (( * (1 - )) / n)
= 2.326 (((0.779*0.221) /517 )
= 0.042
A 98% confidence interval for the proportion is
- E < p < + E
0.779-0.042 < p <0.779+0.042
0.737< p < 0.821
98% confidence interval for the proportion of music teachers who believe that these video games have a positive effect is
(0.737 , 0.821)
lower bound 0.737
upper bound 0.821