For the standard normal probability distribution, the area to the left of the mean is

greater than 0.5

-0.5

one

0.5

none of the above

If a z value is to the left of the mean, then its value is

negative

positive

any value between -¥to ¥

zero

e. none of the above

Assume z is a standard normal random variable. P(-1.50 < z < 1.90) equals

0.0381

0.9045

-0.0381

0.4

e. none of the above

Assume z is a standard normal random variable. P(-2.0 < z < -1.0) equals

a. 0.8185

b. 0.1469

c. 1.0000

d. 0.1359

e. none of the above

Assume z is the standard normal random variable. If the area between zero and z is 0.4115, then the z value may be

2.70

1.35

1.00

0.2077

none of the above

The travel time for a businesswoman traveling between Dallas and Fort Worth is uniformly distributed between 40 and 90 minutes. The probability that she will finish her trip in 80 minutes or less is

0.02

0.2

0.8

1.0

none of the above

A standard normal distribution is a normal distribution

with a mean of 1 and a standard deviation of 0

with any mean and any standard deviation

with a mean of 0 and any standard deviation

with a mean of 0 and a standard deviation of 1

none of the above

A normal probability distribution

is a discrete probability distribution

is a continuous probability distribution

can be either continuous or discrete

must always have a mean of zero

none of the above

The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 miles and a standard deviation of 5,000 miles. What is the probability that a randomly selected tire will have a life of at least 30,000 miles?