Question

6. An engineer for an industrial components manufacturer is planning to buy a new machine. The engineer decides that the new machine will be purchased if there is evidence that the parts produced have a higher average breaking strength than those generated from the old machine. A sample of 20 parts taken from the old machine indicates a mean of 65 kilograms and standard deviation is 6.4 kilograms. A sample of 21 parts from the new machine yields a mean of 72 kilograms and a standard deviation of 6.1 kilograms. i. Based on this sample, should the engineer buy the new machine? Test at 2% significance level. Assume the observations from the two populations are normally distributed and have a common variance of five. [6 marks] ii. Would the engineer change his decision in part (i.) if the significance level is increased to 0.05? [2 marks]

          6. An engineer for an industrial components manufacturer is planning to buy a new machine. The
engineer decides that the new machine will be purchased if there is evidence that the parts
produced have a higher average breaking strength than those generated from the old machine.
A sample of 20 parts taken from the old machine indicates a mean of 65 kilograms and standard
deviation is 6.4 kilograms. A sample of 21 parts from the new machine yields a mean of 72
kilograms and a standard deviation of 6.1 kilograms.
i. Based on this sample, should the engineer buy the new machine? Test at 2% significance
level. Assume the observations from the two populations are normally distributed and have
a common variance of five.
[6 marks]
ii. Would the engineer change his decision in part (i.) if the significance level is increased to
0.05?
[2 marks]

6. An engineer for an industrial components manufacturer is planning to buy a new machine. The
engineer decides that the new machine will be purchased if there is evidence that the parts
produced have a higher average breaking strength than those generated from the old machine.
A sample of 20 parts taken from the old machine indicates a mean of 65 kilograms and standard
deviation is 6.4 kilograms. A sample of 21 parts from the new machine yields a mean of 72
kilograms and a standard deviation of 6.1 kilograms.
i. Based on this sample, should the engineer buy the new machine? Test at 2% significance
level. Assume the observations from the two populations are normally distributed and have
a common variance of five.
[6 marks]
ii. Would the engineer change his decision in part (i.) if the significance level is increased to
0.05?
[2 marks]

Added by Richard W.

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