In: Statistics and Probability
A manufacturer of banana chips would like to know whether its bag filling machine works correctly at the 427427 gram setting. It is believed that the machine is underfilling the bags. A 1515 bag sample had a mean of 421421 grams with a standard deviation of 2828. A level of significance of 0.050.05 will be used. Assume the population distribution is approximately normal. Determine the decision rule for rejecting the null hypothesis. Round your answer to three decimal places.
This is a two tailed test.
The null and alternative hypothesis is,
Ho: 427
Ha: 427
The test statistics,
t =( - )/ (s /n)
= ( 421 - 427 ) / ( 28 / 15 )
= -0.830
Critical value of the significance level is α = 0.05, and the critical value for a two-tailed test is
= 2.145
The decision rule is,
|t| > 2.145.
Since it is observed that |t| = 0.830 < = 2.145 it is then concluded that fail to reject the null hypothesis.