Question

A random sample of 30 varieties of cereal was selected. The average number of calories per serving for these cereals is x-120. Assuming that σ = 10, find a 95% confidence interval for the mean number of calories, μ, in a serving of cereal. a. 115.30 to 124.70 b. 116.42 to 123.58 c. 118.00 to 122.00 d. 117.00 to 123.00

Answer 1

Answer: confidence interval = b. ( 116.42 to 123.58)

Explanation:

Given;

Number of samples n = 30

Standard deviation r = 10

Mean x = 120

Confidence interval of 95%

Z' = t(0.025) = 1.96

Confidence interval = x +/- Z'(r/√n)

= 120 +/- 1.96(10/√30)

= 120 +/- 3.58

= ( 116.42, 123.58)