Stats 1 Final Exam

Which of the following is not a characteristic of the normal probability distribution?

• it is symmetrical

• the total area under the curve is always equal to 1.

• 99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean

• the mean is equal to the median, which is also equal to the mode.

A population characteristic, such as a population mean, is called

• Sample

• Statistic

• parameter
• the mean deviation

The probability that a continuous random variable takes any specific value

• is equal to zero

• is at least 0.5

• depends on the probability density function

• is very close to 1.0

A negative value of Z indicates that

• the number of standard deviations of an observation is to the right of the mean

• the number of standard deviations of an observation is to the left of the mean

• a mistake has been made in computations, since Z cannot be negative

• the data has a negative mean

If we consider the simple random sampling process as an experiment, the sample mean is

• always zero

• always smaller than the population mean

• a random variable

• exactly equal to the population mean

A theorem that allows us to use the normal probability distribution to approximate the sampling distribution of sample means and sample proportions whenever the sample size is large is known as the

• approximation theorem

• normal probability theorem

• central limit theorem

• central normality theorem

A continuous random variable may assume

• any value in an interval or collection of intervals

• only integer values in an interval or collection of intervals

• only fractional values in an interval or collection of intervals

• only the positive integer values in an interval

In computing the standard error of the mean, the finite population correction factor is used when

• N/n > 0.05

• N/n < 0.05

• n/N > 0.05

• n/N=30

A normal distribution with a mean of 0 and a standard deviation of 1 is called

• a probability density function

• an ordinary normal curve

• a nonstandard abnormal distribution

• a standard normal distribution

Variance is

• a measure of the average, or central value of a random variable

• a measure of the dispersion of a random variable

• the square root of the standard deviation

• the sum of the squared deviation of data elements from the mean