This Question: 1 pt vny A researcher studying public opinion of proposed Social

Question

This Question: 1 pt vny A researcher studying public opinion of proposed Social changes obtains a simple sample Americans and asks them whether or not they support the proposed changes. To say that the Security who yes, is approximately normal. how many more adult distribution of the sample proportion of adults respond Americans does the researcher need to sample in the following cases? (a) 10% of Gault Americans support the changes all (b) 15% of all adult Americans support the changes (a) The researcher must ask more American adults. (Round up to the nearest integer) (b) The researcher must ask more American adults. (Round up to the nearest integer) or Succe media Libt ase optio

Explanation / Answer

Solution:

1.
a) 10% of all adult Americans support the changes

n=10/p(1-p) =10/0.1*0.9 =111.11 = 111(rounded up)

More sample needed 111-25 =86
The researcher must ask 86 more American adults.

b) 15% of all adult Americans support changes

n=10/p(1-p) =10/0.15*0.85 =78.43=78(rounded up)

More sample needed 78-25 =53
The researcher must ask 53 more American adults.

2.
a) B. The sample size needs to be greater than or equal to 30.
b) P( x<15 ) = P((x)/(s/n)) <(1516.1)/(4.2/35))
= P(Z<-1.55) = 10.9394=0.0606
c) Calculate the mean oil-change time would there be a 10% chance of being at or below.
P( x <x) = 0.10
P((x)/(s/n)) (a16.1)/(4.2/35)) = 0.10
P((x)/(s/n)) (a16.1)/(0.7099)) = 0.10
Observe that the value corresponding to 0.10(left tailed) cumulative probabilities is -1.286
a16.1/0.7099 = -1.286
a16.1 = -1.286 * 0.7099 = -0.9129
a = -0.9129 +16.1
= 15.1871

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