# 42
The accounting department at Weston Materials, Inc., a national manufacturer of unattached
garages, reports that it takes two construction workers a mean of 32 hours and
a standard deviation of 2 hours to erect the Red Barn model. Assume the assembly times
follow the normal distribution.
a. Determine the z values for 29 and 34 hours. What percent of the garages take between
32 hours and 34 hours to erect?
b. What percent of the garages take between 29 hours and 34 hours to erect?
c. What percent of the garages take 28.7 hours or less to erect?
d. Of the garages, 5 percent take how many hours or more to erect?

Shaver Manufacturing, Inc., offers dental insurance to its employees. A recent study by the
human resource director shows the annual cost per employee per year followed the normal
probability distribution, with a mean of $1,280 and a standard deviation of $420 per year.
a. What fraction of the employees cost more than $1,500 per year for dental expenses?
b. What fraction of the employees cost between $1,500 and $2,000 per year?
c. Estimate the percent that did not have any dental expense.
d. What was the cost for the 10 percent of employees who incurred the highest dental
expense?

Solution Preview

The solution, presented in a Word document, provides detailed guidelines and ...

Solution Summary

The solution provides guidelines and steps for determining the probability, of events, through the use of the normal distribution.

If x is normally distrubed with u = 20.0 and o = 4.0, determine the following:
a. P(x > 20.0)
b. P(16.0 < x < 24.0)
c. P(X < 12)
d. P(x = 22.0)
e. P(12.0 , x , 28.0)
f. P(x 15)

A continuous random variable, x, is normally distributed with a mean of $1000 and a standard deviation of $100. Convert each of the following x values into its corresponding z-score.
a. x = $1000
b. x = $750
c. x = $1100
d. x = $950
e. x = $1225
2.Usingthe standard normal table, find the following probabilities

Assume a binomial probability distribution has µ=0.60 and n= 200
a. What is the mean and standard deviation?
b. Is this a situation in which binomial probabilities can be approximated by thenormal probability distribution? Explain
c. What is the probability of 100 to 110 successes?
d. What is the probability of 130 or

Determine if thenormal approximation to the binomial distribution could be used forthe following problems:
A.) A study found that 1% of Social Security recipients are too young to vote. 800 Social Security recipients are randomly selected.
B.) A study found that 30% of the people in a community use the library in one yea

A normaldistribution has a mean of u= 40 and o=10. if a vertical line is drawn through thedistribution at x= 55, what proportion of the scores on the right side of the line?
A normaldistribution has a u= 80 and o= 10. what is the probability of randomly selecting a score greater than 90 from this distribution?
A normal

Suppose 5.9% of certain population use public transportation to get to work. You randomly select 380 workers and ask them if they use public transportation to get to work. Use thenormaldistribution to approximate the following probabilities.
1) find the probability that exactly 25 workers will say yes.
2) at least 25 wo

The breaking strength of a rivet has a mean value of 10,000 psi and a standard deviation of 500 psi.
a. What is the probability that the sample mean breaking strength for a random sample of 40 rivets is between 9900 and 10,200.
b. If the sample size had been 15 rather than 40, could the probability requested in part (a) b