Introduction to Normal Distributions Answers

The heights of a certain type of tree are approximately normally distributed with a mean height = 5 ft and a standard deviation = 0.4 ft. Which statement must be true?

The graph below shows the average daily temperatures on January 1 from 1900 to 1934 for city A.The mean of the temperatures in the chart is 24° with standard deviation of 4°. How many years had temperatures within one standard deviation of the mean?

What is the mean of the normal distribution shown below?

The lengths of a certain species of fish are approximately normally distributed with a given mean and standard deviation . According to the Empirical Rule, what percentage of the fish will have lengths within 1 standard deviation of the mean?

The graph below shows three different normal distributions.Which statement must be true?

The class scores of a history test have a normal distribution with a mean = 79 and a standard deviation = 7. If Opal’s test score was 72, which expression would she write to find the z-score of her test score?

What is the mean of the normal distribution shown below?

The amount of daily time that teenagers spend on a brand A cell phone is normally distributed with a given mean = 2.5 hr and standard deviation = 0.6 hr. What percentage of the teenagers spend more than 3.1 hr?

The annual salaries of all employees at a financial company are normally distributed with a mean of $34,000 and a standard deviation of $4,000. What is the z-score of a company employee who makes an annual salary of $54,000?

The weights of 2-pound bags of Best Dog Food are approximately normally distributed with a given mean and standard deviation . According to the Empirical Rule, what percentage of the bags will have weights within 3 standard deviations of the mean?