Question

A manufacturer of potato chips would like to know whether its bag filling machine works correctly at the 402 gram setting. It is believed that the machine is underfilling or overfilling the bags. A 13 bag sample had a mean of 409 grams with a standard deviation of 13 Assume the population is normally distributed. A level of significance of 0.1 will be used. Specify the type of hypothesis test.

Answer 1

H0: = 402

Ha: 402

Test statistics

t = ( - ) / ( S / sqrt(n) )

= ( 409 - 402 ) / (13 / sqrt(13) )

= 1.94

df = n - 1 = 13 - 1 = 12

From T table,

t critical value at 0.1 significance level with 12 df = 1.782

Since test statistics > 1.782, Reject H0

We conclude that we have sufficient evidence to support the claim that  the machine is

underfilling or overfilling the bags.