The lifetime of a certain brand of batteries are known to be normally distributed with a mean of 1600 hours and a standard deviation of 400 hours. A random sample of 64 of these batteries is taken. What is the probability that the sample mean lifetime is more than 1500 hours?

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The lifetime of a certain brand of batteries are known to be normally distributed with a mean of 1600 hours and a standard deviation of 400 hours. A random sample of 64 of these batteries ...

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The solution uses a random sample of 64 batteries to find the probably and sample mean of the lifetime of the batteries.

If 10% of all disk drives produced on an assembly line are defective,
a. What is the probability that there will be exactly one defect in a random sample of 5 of these?
b. What is the probability that there will be no defects in a random sample of 5?

1. An economist wishes to estimate the average family income in a certain population. The population standard deviation is known to be $4,500, and the economist uses a random sample of size = 225.
a. What is the probability that the samplemean will fall within $800 of the population mean?
b. What is the probability that the

The Oil Price Information Center reports the mean price per gallon of regular gasoline is 3.26 with a population standard deviation of 0.18. Assume a random sample of 40 gasoline stations is selected and their mean cost for regular gasoline is computed.
a.) What is the standard error of the mean in this experiment?
b.) What

The average price of a gallon of unleaded regular gasoline was reported to be $3.13 in Illinois (http://www.cincygasprices.com).
Use this price as the population mean, and assume the population standard deviation is $.20.
A) What is the probability that the mean price for a sample of 30 service stations is within $.03 of

The shelf life of a digital storage device is normally distributed with mean 10 years and standard deviation 2 years. Suppose you are a quality assurance manager and wish to verify this statistic. You choose a sample of 25 storage devices sold in the last 10 years. Supply the following information: Describe the sampling distribu

A carton of 6 batteries contains 2 that are defective and 4 that are good.
If we select 3 batteries at random form this carton, what is the probability that the sample contains exactly 1 defective battery?
a) 33.3%
b) 50.0%
c) 60.0%

In a large university, 15% of the students are female. If a random sample of twenty students is selected,
a. what is the probability that the sample contains exactly four female students?
b. what is the probability that the sample will contain no female students?
c. what is the probability that the sample will contain

The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000. What percentage of MBA's will have starting salaries of $34,000 to $46,000?
The weights of items produced by a machine are normally distributed with a mean of 8 ounces and a standard de

Which of the following is a valid probability distribution for a sample space
S = {a,b,c,d}
a. Pr(a)=-0.2, Pr(b)=0.5, Pr(c)=0.4, Pr(d)=0.3
b. Pr(a)=0.3, PR(b)=0.1, Pr(c)-0.2, Pr(d)=0.5
c. Pr(a)=0.6, Pr(b)=0, Pr(c)=0.3, Pr(d)=0.1
d. Pr(a)=0.5, Pr(b)=0.2, Pr(c)=0.1, Pr(d)=0.3