Chapter 6: Continuous Probability Distributions

A bicyclist's one-way commute time is uniformly distributed between 40 and 50 minutes. What is the probability that the commute takes between 44 and 46 minutes?
1. 0.2000
2. 0.2736
3. 0.7264
4. 45 minutes
5. None of the above
A bicyclist's one-way commute time is uniformly distributed between 40 and 50 minutes. What is the expected commute time?
1. 5 minutes
2. 8.33 minutes
3. 45 minutes
4. 50 minutes
5. None of the above
Let z be a normally distributed random variable. Find P(z > 2.54).
1. 0.0055
2. 0.0254
3. 0.4945
4. 0.9945
5. None of the above
Let z be a normally distributed random variable. Find ( - 2 ≤ z ≤ 1.04).
1. 0.1720
2. 0.3508
3. 0.4772
4. 0.8280
5. None of the above
The wind speed at a wind energy farm is approximately normally distributed with a mean of 25 miles per hour and a standard deviation of 7 miles per hour. What percent of the time will the wind speed be below 15 miles per hour?
1. 7.64%
2. 42.36%
3. 57.64%
4. 92.36%
5. None of the above
The wind speed at a wind energy farm is approximately normally distributed with a mean of 25 miles per hour and a standard deviation of 7 miles per hour. When wind speeds exceed 45 miles per hour, the wind farm produces too much electricity for the current transmission lines and must be shut down. What percentage of the time will winds exceed 45 miles per hour?
1. 0.21%
2. 2.1%
3. 9.79%
4. 28.6%
5. None of the above
In order to uniquely define a normal distribution, one must know
1. μ
2. n
3. σ
4. both a and c
5. a, b and c
The most important distribution in statistics is the
1. binomial
2. exponential
3. normal
4. Poisson
5. None of the above
An instructor curves the class grades so that the top 10% of the students in class receive an A for the semester. During the past semester, the grades were approximately normally distributed with a mean of 217 points and a standard deviation of 32 points. How many points were needed to earn an A for the semester?
1. 217
2. 230
3. 251
4. 258
x is a normally distributed random variable with a mean of 27 and a standard deviation of 3. Find P(27 < x < 33).
1. 0.4772
2. 0.5000
3. 0.5228
4. 0.9772
5. None of the above
Which of the following is an example of a continuous distribution?
1. Binomial
2. Exponential
3. Poisson
4. Both a and c are continuous
5. None of the above
The graph of which of the following distributions is bell-shaped?
1. Exponential
2. Normal
3. Uniform
4. All of the above
The graph of which of the following distributions is flat?
1. Exponential
2. Normal
3. Uniform
4. None of the above
A certain manufacturer's bicycle pedal sealed-bearing set's lifetime is exponentially distributed with a mean of 5 years. What is the probability that a sealed-bearing set lasts longer than 6 years?
1. 0.3012
2. 0.4346
3. 0.5654
4. 0.6988
5. None of the above
A certain manufacturer's bicycle pedal sealed-bearing set's lifetime is exponentially distributed with a mean of 5 years. What is the probability that a sealed-bearing set lasts between 3 and 5 years?
1. 0.0833
2. 0.1809
3. 0.4512
4. 0.6321
5. None of the above