**In Exercise 9-20, find the boundary of the critical region if the type I error probability…**

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## Question “In Exercise 9-20, find the boundary of the critical region if the type I error probability…”

In Exercise 9-20, find the boundary of the critical region if the type I error probability is

9-20 A manufacturer is interested in the output voltage of a power supply used in a PC. Output voltage is assumed to be normally distributed with standard deviation 0.25 volt, and the manufacturer wishes to test volts, using n = 8 units.

## Answer

(a) Let denote critical values.

The distribution of the sample means is roughly normal with the , and the standard deviation

The *z_*values which correspond to the critical * values are*

We find that using the Cumulative Normal Distribution table, we can calculate and. Therefore,

The acceptance zone is therefore

.

. Therefore,

We find

and

in the Cumulative Normal Distribution table. Therefore,

The acceptance zone is therefore

.

(c) *n =*16.

The *z*values which correspond to the critical values

are

. Therefore,

We find

and

in the Cumulative Normal Distribution table. Therefore,

The acceptance zone is therefore

.

. Therefore,

We find

and

in the Cumulative Normal Distribution table. Therefore,

The acceptance zone is therefore

.

## Conclusion

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