The management are concerned about the night shift. They re-engineer the production process and then take a sample of 200 cans. They want to know if the mean weight of peaches in the cans produced by the night shift after the change (Night shift 2) is different than before the change (Night shift 1)

Sample size

Mean weight

Variance

Night shift (1)

100

315g

225

Night shift (2)

200

320

150

(a) Describe the test that you would use to see if the change has changed the mean number of peaches in the cans?[1 point]

(b) At the 95% confidence level Is there evidence that the mean weight of the later night-shift cans(night shift 2)is different than the mean weight of the original night shift cans (night shift 1) ?[5 marks]

Write down a null and alternative hypothesis

H0:.......................................

HA: ..................................................

(you can use MEAN_1, MEAN_2 for the means, VAR for variance,VAR(EST) for the estimated variance, SDor SD(EST) for the standard deviation or the estimated standard deviation etc and (le, ne, ge) for ()). Also if you multiply or divide in the formula use (x, /).

Write down the value of the test statistic you calculate, showing how you calculated it.

Indicate the value of the numerator and the denominators of any test statistic you calculate

.........................................................

Write down the degrees of freedom for the test and the critical value or values. If the table in the front of the book doesn't have the correct number, use the closest degrees of freedom.

Do you reject the null hypothesis ? .........................................