In which situation may the sample proportion safely be assumed to follow a normal distribution? Select...

In which situation may the sample proportion safely be assumed to follow a normal distribution?

Select one:

a. 8 successes in a sample of 72 items.

b. 5 successes in a sample of 20 items.

c. 9 successes in a sample of 200 items.

d. 12 successes in a sample of 500 items.

Solutions

Expert Solution

a. Here p=8/72=0.1111 and n=72 so np=8<10

So it is not normal

b. Here p=5/20=0.25 and n=20, so np=20*0.25=5<10

So it is not normal

c. Here p=9/200=0.045 and n=200, so np=200*0.045=9

So it is not normal

d. Here p=12/500=0.0240 and n=500, so np=500*0.0240=12>10

Hence it is normal

orchestra answered 1 year ago

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