MATH221 Week 4 Questions with Verified Solutions Rated A+ Latest Update 2025
The speed of cars on a stretch of road is normally distributed with an average 40 miles per hour with a standard deviation of 5.9 miles per hour. What is the probability that a randomly selected car is violating the speed...
The speed of cars on a stretch of road is normally distributed with an average 40 miles per hour with a
standard deviation of 5.9 miles per hour. What is the probability that a randomly selected car is violating
the speed limit of 50 miles per hour? - Answers 0.05
A survey indicates that shoppers spend an average of 26 minutes with a standard deviation of 8 minutes
in your store and that these times are normally distributed. Find the probability that a randomly
selected shopper will spend less than 20 minutes in the store. - Answers 0.23
The monthly utility bills in a city are normally distributed with a mean of $121 and a standard deviation
of $23. Find the probability that a randomly selected utility bill is between $115 and $130. - Answers
0.255
In a normally distributed data set of how long customers stay in your store, the mean is 50.3 minutes
and the standard deviation is 3.6 minutes. Within what range would you expect 95% of your customers
to stay in your store? - Answers 43.1-57.5
In a normally distributed data set with a mean of 19 and a standard deviation of 2.6, what percentage of
the data would be between 16.4 and 21.6? - Answers 68% based on the Empirical Rule
A restaurant serves hot chocolate that has a mean temperature of 175 degrees with a standard
deviation of 8.1 degrees. Find the probability that a randomly selected cup of hot chocolate would have
a temperature of less than 161 degrees. Would this outcome warrant a replacement cup (meaning that
it would be unusual)? - Answers Probability of 0.04 and would warrant a refund
On average, the parts from a supplier have a mean of 97.5 inches and a standard deviation of 6.1 inches.
Find the probability that a randomly selected part from this supplier will have a value between 85.3 and
109.7 inches. Use the Empirical Rule of 68%-95%-99.7%. - Answers Probability is 0.95
A process is normally distributed with a mean of 104 rotations per minute and a standard deviation of
8.2 rotations per minute. If a randomly selected minute has 129 rotations per minute, would the process
be considered in control or out of control? - Answers Out of control as this one data point is more than
three standard deviations from the mean
The soup produced by a company has a salt level that is normally distributed with a mean of 5.4 grams
and a standard deviation of 0.3 grams. The company takes readings of every 10th bar off the production
line. The reading points are 5.8, 5.9, 4.9, 5.2, 5.0, 4.9, 6.2, 5.1, 5.7, 6.1. Is the process in control or out of
control and why? - Answers It is in control as the data points more than 2 standard deviations from the
mean are far apart
The blenders produced by a company have a normally distributed life span with a mean of 8.2 years and
a standard deviation of 1.3 years. The company is willing to have a warranty that replaces at most 6% of
their blenders sold. What is the longest a blender can last and still be in the lowest 6% of life spans? -
Answers 6.2 years
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