Question

A random sample of 26 fields of spring wheat has a mean yield of 32.4 bushels per acre and standard deviation of 1.42 bushels per acre. Determine the 98% confidence interval for the true mean yield. Assume the population is approximately normal.

Step 2 of 2 :  

Construct the 98% confidence interval. Round your answer to one decimal place.

Answer 1

Formula for Confidence Interval for Population mean when population Standard deviation is not known

for 98% confidence level = (100-98)/100 =0.02

/2 =0.02/2=0.01

Number of fields of spring wheat in the sample : Sample Size : n=26

Degrees of freedom = n-1 = 26-1 =25

Sample mean yield : = 32.4

Sample standard deviation : s=1.42

98% confidence interval for the true mean yield

98% confidence interval for the true mean yield = (31.7, 33.1)