Question 8 (1 point)
1 answer:
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Answer:
Step-by-step explanation:
Given that in a sample of 800 U.S. adults, 199 think that most celebrities are good role models. Two Two U.S. adults are selected at random from the population of all U.S. adults without replacement.
In 800 adults 199 are favourable and remaining 601 are against.
a) The probability that both adults think most celebrities are good role models is ________= Prob of selecting both from 199
=
=0.062
b) The probability that neither adult thinks most celebrities are good role models is _______=P(both selecting from 601)
=
=0.564
c) The probability that at least one of the two adults thinks most celebrities are good role models ______
=1-Prob that neither thinks
= 1- 0.564
= 0.436
Answer:
The 90% confidence interval for the true mean lifetime of all batteries of this brand is between 39.3 hours and 41.7 hours. The lower limit is 39.3 hours while the upper limit is 41.7 hours.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
That is z with a pvalue of , so Z = 1.645.
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 40.5 - 1.2 = 39.3 hours
The upper end of the interval is the sample mean added to M. So it is 40.5 + 1.2 = 41.7 hours
The 90% confidence interval for the true mean lifetime of all batteries of this brand is between 39.3 hours and 41.7 hours. The lower limit is 39.3 hours while the upper limit is 41.7 hours.