All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.

(i)

Let be the population mean time taken to install an electronic component.

(ii)

Under

Test Statistic,

At 5% level of significance, we reject if

(iii)

At 5% level of significance, we do not reject if

### KS Comments:

Some students forget to define appropriately. (ii), a few students actually do not realised that the rejection rule is when instead of , and did not consider the correct inequality. (iii), Students overlook that n refers to sample size and sample size must be an integer. The answers are required to be given in sets here. Some students still have trouble writing sets.

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