# Statistics homework – multiple choice questions

1) When referring to the normal probability distribution, there is not just one; there is a “family” of distributions.

True

or

False

2) The standard normal probability distribution is unique because it has:

Choose one:

Any mean and a standard deviation of 1

-A mean of 0 and any standard deviation

-A mean of 0 and a standard deviation of 1

-A mean of 1 and any standard deviation

3) Tables of normal distribution probabilities are found in many statistics books. These probabilities are calculated from a normal distribution with. Choose one:

a mean of 100 and a standard deviation of 15

a mean of 1 and a standard deviation of 1

a mean of 0 and a standard deviation of 1

a mean of 0 and a standard deviation of 15

4) What is the percentage of the total area under the normal curve within plus and minus two standard deviations of the mean? Choose one:

34.13%

68.26%

99.74%

95.44%

5) The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the probability that a flight is between 125 and 140 minutes? Choose one:

1.00

0.333 minutes

0.5

10 minutes

6) If an average of 12 customers are served per hour, then one customer arrives every. Choose one.

5 minutes

10 minutes

60 minutes

12 minutes

7) In a uniform probability distribution, P(x) is constant between the distribution’s minimum and maximum values.

True

or

False

8) The total area of a normal probability distribution is. Choose one:

-approximated by the binomial distribution.

-1.00.

-dependent on a value of ‘z’.

-between -3.0 and 3.0.

9) The shape of any uniform probability distribution is. Choose one:

-Positively skewed

-Rectangular

-Negatively skewed

-Bell shaped

10) The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the mean? Choose one:

-150 minutes

-120 minutes

-270 minutes

-135 minutes

11) For the exponential distribution, the mean and standard deviation are equal.

True

or

False

12) Some normal probability distributions have equal arithmetic means, but their standard deviations may be different.

True

or

False

13) A random variable from an experiment where outcomes are normally distributed. Choose one:

-can have a mean of 0 and a standard deviation of 1.

-can have only a few discrete values.

-can have no values.

-can have any value between – ∞ and + ∞.

14) If an average of 60 customers are served per hour, then one customer arrives every. Choose one:

-1 minute

-12 minutes

-60 minutes

-10 minutes

15) What is a normal distribution with a mean of 0 and a standard deviation of 1 called? Choose one:

-Binomial probability distribution

-Standard normal distribution

-Frequency distribution

-Z-score

16) A binomial distribution has 50 trials (n = 50) with a probability of success of 0.50 (π=0.50). To use the normal distribution to approximate the binomial, what are the mean and standard deviation? Choose one?

µ =25 and σ = 4.33

µ =25 and σ = 12.5

µ = 25 and σ = 3.5355

µ =50 and σ = 100

17) In an illustration of a normal probability distribution, a shaded area represents. Choose one:

-a probability

-a combination

-a standard deviation

-a permutation

18) Two normal distributions are compared. One has a mean of 10 and a standard deviation of 10. The second normal distribution has a mean of 10 and a standard deviation of 2. Which of the following is true?

-The distributions are from two different families of distributions

-The dispersions of the distributions are different

-The dispersions of the distributions are the same

-The locations of the distributions are different

19) The area under the normal curve within plus and minus one standard deviation of the mean is about 68.26%.

True

or

False

20) The standard deviation of any uniform probability distribution is. Choose one of the following:

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