A student wanted to estimate the number of chocolate chips in a commercial brand of cookie. he sampled 100 cookies and found an average of 10.5 chips per cookie. if we assume the standard deviation is 8, what is a 99% confidence interval for the average number of chips per cookie?

Question

Ronan Farrell

Mathematics

15 October, 19:20

A student wanted to estimate the number of chocolate chips in a commercial brand of cookie. he sampled 100 cookies and found an average of 10.5 chips per cookie. if we assume the standard deviation is 8, what is a 99% confidence interval for the average number of chips per cookie?

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Paloma · Answer 1

To find the interval we use the formula:

x'+/-2.58σ/√n

where:

x' = sample mean=10.5

2.58=table value at 99% confidence

σ=population standard deviation=8

n=100

substituting the values we get:

(10.5+/-2.58*0.08) / √100

= (10.5+/-2.064) / 10

= (10.5+2.064,10.5-2.064) / 100

= (0.126, 0.084)