Question

Twenty cans of soda were randomly selected with an average of 32.6 mg of caffeine.

The sample standard deviation is 20.33 mg. Use these data to find a 99% confidence

interval. Also, find the estimation and margin of error.

Answer 1

c )solution

Given that,

= 32.6

s =20.33

n = 20

Degrees of freedom = df = n - 1 = 20 - 1 = 19

At 99% confidence level the t is ,

= 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

t /2  df = t0.005,19 = 2.861 ( using student t table)

Margin of error = E = t/2,df * (s /n)

= 2.861* ( 20.33/ 20) = 13.0