Question

A manufacturer of potato chips would like to know whether its bag filling machine works correctly at the 443 gram setting. It is believed that the machine is underfilling the bags. A 44 bag sample had a mean of 437 grams. Assume the population standard deviation is known to be 23. A level of significance of 0.05 will be used. State the null and alternative hypotheses.

Answer 1

The null and alternative hypothesis are

H0: = 443

Ha: < 443

Test statistics

z = - / / sqrt(n)

= 437 - 443 / 23 / sqrt(44)

= -1.73

This is test statistics value.

Critical value at 0.05 level is -1.645

Since test statistics falls in rejection region, we have sufficient evidence to reject H0.