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?
Required
2 points
2
Question 2
2.
Approximately what percent of the data in a normal distribution is between the mean and 1 standard deviation below the mean?
Required
2 points
2
Question 3
3.
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.
Required
2 points
2
Question 4
4.
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?
Required
2 points
2
Question 5
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 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.
Required
2 points
2
Question 6
6.
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?
Required
2 points
2
Question 7
7.
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.
Required
2 points
2
Question 8
8.
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?
Required
2 points
2
Question 9
9.
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?
Required
2 points
2
Question 10
10.
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 _______ or a test score more than _______ .
Required
2 points
2
Question 11
11.
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
Required
2 points
2
Question 12
12.
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.
Determine the percentage of batteries with a lifetime between 51.8 and 60.2 hours
Required
1 point
1
Question 14
14.
PART C:
Determine the percentage of batteries with a lifetime less than 51.8 hours.
Required
4 points
4
Question 15
15.
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?