In: Statistics and Probability
A study of 100 apple trees showed that the average number of apples per tree was 1,000. The standard deviation of the population is 150. Which of the following is the 95% confidence interval for the mean number of apples for all trees? a.) (975.3, 1024.7) B.) (970.6, 1029.4) C.) (967.7, 1032.3) D.) (965.1, 1034.9)
Solution :
Given that,
= 1000
= 150
n = 100
At 95% confidence level the z is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
Z/2 = Z0.025 = 1.96
Margin of error = E = Z/2* ( /n)
= 1.96 * (150 / 100)
= 29.4
At 95% confidence interval estimate of the population mean is,
- E < < + E
1000 - 29.4 < < 1000 + 29.4
970.6 < < 1029.4
(970.6 , 1029.4)
Option B) is correct