13.A college professor noted that the grades of his students in an introductory statistics class were normally distributed with a mean of 76.5 and a standard deviation of 9. If 67.36% of his students received grades of C or above, what is the minimum score of those students receiving a grade of at least a C?

1. 67.36
2. 72.45
3. 66.56
4. 70.00

14.The seasonal output of a new experimental strain of pepper plants was carefully weighed. The mean weight per plant is 15.0 pounds, and the standard deviation of the normally distributed weights is 1.75 pounds. Of the 200 plants in the experiment, how many produced peppers weighing between 13 and 16 pounds?

1. 100
2. 118
3. 197
4. 53

15.What is the probability thatzis between 0.0 and 2.0?

1. 1.0000
2. 0.7408
3. 0.1359
4. 0.4772

16.Which of the following is a characteristic of the normal probability distribution?

It's positively skewed.

It's bell-shaped.

It's asymmetrical.

It's rectangular.

17.Tables of normal distribution probabilities are found in many statistics books. These probabilities are calculated from a normal distribution with ___________.

1. A mean of 1 and a standard deviation of 1
2. A mean of 100 and a standard deviation of 15
3. A mean of 0 and a standard deviation of 15
4. A mean of 0 and a standard deviation of 1

18.If an average of 12 customers is served per hour, what is the probability that the next customer will arrive in 6 minutes or less?

1. 0.61
2. 0.30
3. 0.70
4. 0.39

19.A cola-dispensing machine is set to dispense a mean of 2.02 liters into a container labeled 2 liters. Actual quantities dispensed vary and the amounts are normally distributed with a standard deviation of 0.015 liters. What is the probability a container will have less than 2 liters?

1. 0.0918
2. 0.3413
3. 0.1926
4. 0.8741

20.Which of the following is true regarding the normal distribution?

The mean, median, and mode are all equal

.It has two modes.

It is asymmetrical.

The points of the curve meet thex-axis atz= -3 andz= 3.

21.A binomial distribution has 100 trials (n = 100) with a probability of success of 0.25 ( = 0.25). We would like to find the probability of 75 or more successes using the normal distribution to approximate the binomial. Applying the continuity correction factor, what value would be used to calculate a z-score?

1. 74.5
2. 75
3. 75.5
4. 25

22.The mean of a normal distribution is 400 pounds. The standard deviation is 10 pounds. What is the probability of a weight between 415 pounds and the mean of 400 pounds?

1. 0.5000
2. 0.1932
3. 0.4332
4. 0.3413

23.If an average of 60 customers are served per hour, then one customer arrives every ________.

1. 1 minute
2. 60 minutes
3. 12 minutes
4. 10 minutes

24.Which of the following is true in a normal distribution?

The mean equals zero.

The mode and the third quartile are equal.

The mean divides the distribution into two equal areas.

The area under the curve is 0.68.

25.The upper and lower limits of a uniform probability distribution are __________.

1. Positive and negative infinity
2. Plus and minus three standard deviations
3. 0 and 1
4. The maximum and minimum values of the random variable