Download The lifetimes of a certain brand of light bulbs are known

Sampling Distributions
Find the indicated probability or percentage for the sampling error.
1) Scores on an aptitude test are normally distributed with a mean of 220 and a standard
deviation of 30. What is the probability that the sampling error made in estimating the
population mean by the mean of a random sample of 50 test scores will be at most
5 points?
1)
2) The amount of coffee which a filling machine puts into an 8 -ounce jar is normally
distributed with a mean of 8.2 ounces and a standard deviation of 0.18 ounces Determine
the percentage of samples of size 16 that have a mean amount within 0.1 ounces of the
population mean of 8.2 ounces.
2)
3) The monthly expenditures on food by single adults living in one neighborhood of Los
Angeles are normally distributed with a mean of $410 and a standard deviation of $45.
Determine the percentage of samples of size 9 that have mean expenditures within $12 of
the population mean expenditure of $410.
3)
4) The lifetimes of a certain brand of light bulbs are known to be normally distributed
4)
with a mean of 1,600 hours and a standard deviation of 400 hours. A random sample
of 64 of these light bulbs is taken.
What is the number of hours for which the probability that the sample mean lifetime is
greater than the mean is 0.15?
5)
The lifetimes of a certain brand of light bulbs are known to be normally
distributed with a mean of 1,600 hours and a standard deviation of 400 hours. A
random sample of 64 of these light bulbs is taken.
5)
What is the probability that the sample mean lifetime is more than 1,550 hours?
6) According to a survey, only 15% of customers who visited the web site of a major
6)
retail store made a purchase. Random samples of size 50 are selected.
What is the percent of all the sample proportions of customers who will make a
purchase after visiting the web site?
7) According to a survey, only 15% of customers who visited the web site of a major
retail store made a purchase. Random samples of size 50 are selected.
What is the standard deviation of all the sample proportions of customers who will
make a purchase after visiting the web site?
1
7)