The table displays the ages of current employees at the Ace software development company.
If you construct a relative frequency histogram for the data, what will be the height of the bar representing the employees who are 30 – 40 years old?
Approximately what percent of the data in a normal distribution is between the mean and 1 standard deviation below the mean?
The EPA fuel economy estimates for automobile models tested recently predicted a Normal model with a mean of 24.8 mpg and a standard deviation of 6.2 mpg. What percent of cars get less than 20 mpg? Round your answer to the nearest whole percent.
On a social studies test, the average score was 75 and the standard deviation was 5. About 16% of the students scored below what test score?
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 3.5 minutes and a standard deviation of 1 minute, using the Empirical Rule, find the probability that a randomly selected college student will take between 4.5 and 6.5 minutes to find a parking spot in the library parking lot.
The weights of a group of 10-year-old boys are normally distributed with a mean of 70 pounds and a standard deviation of 12 pounds. What is the z-score for a 10-year-old boy who weighs 79 pounds?
The scores on a standardized test given to juniors are normally distributed with a mean of 21 and a standard deviation of 2.2. Which test score is closest to the 80th percentile? Round to the nearest whole value.
Aaron has discovered an error in his credit card bill. The wait times to talk to a supervisor at the credit card company are normally distributed with a mean of 12 minutes and a standard deviation of 1.7 minutes. What is the probability that Aaron will have to wait more than 15 minutes to talk to a supervisor?
A herd of adult giraffes has a mean height of 15.7 feet with a standard deviation of 0.6 foot. The heights are normally distributed. What data value has a z-score of -0.82?
The scores on a standardized mathematics test are normally distributed with a mean of 500 and a standard deviation of 120. Which situation has a probability of 0.16 of occurring for a randomly selected test score?
A test score less than
Given the Normal curves, a, b, c, and d, determine whether the statement is true or false.
True | False | |
|---|---|---|
The mean of a is greater than the mean of c. | ||
The standard deviations of all four curves are equal. | ||
The means of all four curves are equal. | ||
The standard deviation of graph d is the smallest |
The lifetime of a certain type of battery is normally distributed. The battery’s mean lifetime is 56 hours with a standard deviation of 1.4 hours.
PART A: Use the mean and standard deviation to label the intervals on the horizontal axis of the normal curve. Include 3 standard deviations above and below the mean.
PART B:
Determine the percentage of batteries with a lifetime between 51.8 and 60.2 hours
PART C:
Determine the percentage of batteries with a lifetime less than 51.8 hours.
All students who complete the Algebra 2 course at Ridgeway High School take a common final exam. The exam scores are normally distributed with a mean of 69 and a standard deviation of 4. Steve and Kiley are Algebra 2 students who took the final exam. Steve’s score was 78 and Kiley’s score was 62.
a.) Calculate the z-score for each student.
Steve: z=
Kiley: z=
b.) What percent of the students had a final exam score lower than Kiley’s score? (Write your answer as a percent.)
c.) What percent of students who took the exam received scores that fell between Steve’s and Kiley’s scores?
