# Study Giude for Business Statistics

**Topics:**Normal distribution, Sample size, Confidence interval

**Pages:**18 (5040 words)

**Published:**February 10, 2013

2.If the margin of error in an interval estimate of μ is 4.6, the interval estimate equals b.[pic]

3.The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the c.degrees of freedom

4.The probability that the interval estimation procedure will generate an interval that does not contain the actual value of the population parameter being estimated is the a.level of significance

5.To compute the minimum sample size for an interval estimate of μ, we must first determine all of the following except d.degrees of freedom

6.The use of the normal probability distribution as an approximation of the sampling distribution of [pic] is based on the condition that both np and n(1 – p) equal or exceed b.5

7.The sample size that guarantees all estimates of proportions will meet the margin of error requirements is computed using a planning value of p equal to b..50

8.We can reduce the margin of error in an interval estimate of p by doing any of the following except b.increasing the planning value p* to .5

9.In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with

c.n − 1 degrees of freedom

10.The expression used to compute an interval estimate of μ may depend on any of the following factors except d.whether there is sampling error

11.The mean of the t distribution is

a.0

12.An interval estimate is used to estimate

d.a population parameter

13.An estimate of a population parameter that provides an interval believed to contain the value of the parameter is known as the. b.interval estimate 14.As the sample size increases, the margin of error

b.decreases

15.The confidence associated with an interval estimate is called the

c.confidence level

16.The ability of an interval estimate to contain the value of the population parameter is described by the

a.confidence level

17.If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be

c.0.9

18.If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is c.0.95 19.For the interval estimation of ( when ( is assumed known, the proper distribution to use is the

a.standard normal distribution

20.The z value for a 97.8% confidence interval estimation is

d.2.29

21.It is known that the variance of a population equals 1,936. A random sample of 121 has been taken from the population. There is a .95 probability that the sample mean will provide a margin of error of a.7.84 or less

22.A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is b.19.2 to 20.8

Exhibit 8-1

In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 23.Refer to Exhibit 8-1. The standard error of the mean is

d.0.133

24.Refer to Exhibit 8-1. With a 0.95 probability, the margin of error is approximately

a.0.26

25.Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately

d.8.74 to 9.26 hours

Exhibit 8-2

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is one minute. 26.Refer to Exhibit 8-2. The standard...

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