1. The total area under the normal curve is equal to

A.True    B.False

2. A standard normal curve is a normal probability distribution that has a mean of one and a standard deviation of one.
A.False     B.True

3. The normal distribution is a continuous curve and always has a positive value for f(X)f(X) .
A.True     B.False

4. The width of the curve in a normal distribution is determined by the standard deviation of the distribution.
A.False     B.True

5. The normal distribution is at its lowest point at the mean.
A.True     B.False

1. In its standardized form, the normal distribution 

(a) has a mean of 0 and a standard deviation of 1.

(b) has a mean of 1 and a variance of 0.

(c) has an area equal to 0.5.

(d) cannot be used to approximate discrete probability distributions.

2. For some positive value of Z, the probability that a standard normal variable is between 0 and Z is 0.3770.

The value of Z is

(a) 0.18

(b) 0.81

(c) 1.16

(d) 1.47

3. For some value of z, the probability that a standard normal variable is below z is 0.2090. The value of Z is 

(a) -0.81

(b) -0.31

(c) 0.31

(d) 1.96

4. For some positive value of X, the probability that a standard normal variable is between 0 and +2x is 0.1255.

The value of X is 

(a)  0.99

(b) 0.40

(c) 0.32

(d) 0.16

5. If we know that the length of time it takes a college student to find a parking spot in the library parking lot follows a normal distribution with a mean of 35. minutes and a standard deviation of minute, find the probability that a randomly selected college student will find a parking spot in the library parking lot in less than 3 minutes.

(a) 0.3551

(b) 0.3085

(c) 0.2674

(d) 0.1915 

If a normal distribution has a mean of 50 and a standard deviation of 10, what is P(x<40)?

Find the indicated z -score. Be sure to draw a standard normal curve that depicts the solution. Find z-scores that separate the middle 99% of the distribution from the area in the tails of the standard normal distribution.