Introduction to Normal Distributions Answers

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

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 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 set of life spans of an appliance is normally distributed with a mean = 48 months and a standard deviation = 8 months. What is the z-score of an appliance that stopped working at 64 months?

The lengths of a lawn mower part are approximately normally distributed with a given mean = 4 in. and standard deviation = 0.2 in. What percentage of the parts will have lengths between 3.8 in. and 4.2 in.?

What is the mean of the normal distribution shown below?

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 a standard deviation of 4°. Which temperature is within one standard deviation of the mean?

The graph below shows two normal distributions.What is the difference of the means of the distributions?

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?