Statistics Chapter 7

what are the characteristics of a normal distribution

- a family of distributions, each member of which is bell shaped and symmetrical - the distribution of many physical and psychological attributes

In any normal distribution, the mean, median, mode, and standard deviation are all at the same position on the horizontal axis.

False

In the normal distribution, the curve is asymptotic but never intercepts the horizontal axis either to the left or right.

True

In the normal distribution, the total area beneath the curve represents the probability for all possible outcomes for a given event.

True

Under certain conditions, the normal distribution can be used to approximate the binomial distribution.

True

2. Which of the following are not correct concerning the probability distribution for any continuous random variable? a. The vertical coordinate is the probability density function. b. The range of the random variable is found on the y-axis. c. The total area represented under the curve will be equal to 1.00. d. The probability that x will take on a value between a and b will be the area under the curve between points a and b. e. The area under the curve represents the sum of probabilities for all possible outcomes.

b. The range of the random variable is found on the y-axis.

A continuous probability distribution represents a random variable: a. having outcomes, which occur in counting numbers. b. having an infinite number of outcomes which may assume any number of values within an interval. c. which is best described in a histogram. d. which has a definite probability for the occurrence of a given integer. e. None of these is correct.

b. having an infinite number of outcomes which may assume any number of values within an interval.

3. In a continuous probability distribution, the probability that x will take on an exact value: a. is equal to the height of the curve at that value. b. is calculated using the probability density. c. is always equal to 0. d. is always greater than 0. e. None of these is correct.

c. is always equal to 0.