True or False a If the population varriance is increased and

True or False:

a. If the population varriance is increased and other factors are the same, the width of a z confidence interval for the population mean will increase

b. There are different t distributions for different sample sizes

c. Suppose a 95% confidence interval for the mean height of a 12 year old is 54 to 65 inches. It can then be said that 95% of 12 year olds have heights greater than 54 inches and less than 65 inches.

e. s^2 is a statistic

f. As the level of confidence increases the associated confidence intervals will grow wider

g. The margin of error can be determined if you know only the length of a confidence interval

h. The confidence interval for a population mean can be obtained if the experimenter knows only the margin of error and the sample mean

i. The margin of error depends on the confidence level of the confidence interval

Solution

a)

TRUE. This will increase the margin of error.

b)

TRUE. This depends on the number of degreees of freedom.

c)

FALSE. This estimates the mean height, not the individual heights.

d)

FALSE. The standard error is just the sigma/sqrt(n), without the 1.96.

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