A factory produces plate glass with a mean thickness of 4mm and a standard deviation of 1.1 mm. A simple random sample of 100 sheets of glass is to be measured, and the mean thickness of the 100 sheets is to be computed. What is the probability that the average thickness of the 100 sheets is less than 3.91 mm?

For a normally distributed random variable the standard deviation is 3.7 what is the mean if 10% of the distribution is less than 31?

The weights of the guinea pigs in a laboratory are normally distributed with a mean weight of 2.1 pounds and a standard deviation of 0.8. What is the probability that a randomly selected guinea pig would weigh above 2.3 pounds?

Suppose the weight of watermelons produced in Adana follows the normal distribution with mean 7.2 kg and standard deviation 2.4. Find the proportion of these watermelons that weight heavier than 7.5kg. If we randomly select one of these watermelons, find the probability that its weight will be less than 7kg.

Blood pressure is distribued Normally, with a mean of 85 mm and a standard deviation of 20 mm. As a research pysician you are randomly assigned 100 patients. What is the probability that the average blood pressure for your sample of 100 patients is greater than 82 mm?

The MPG (miles per gallon) for a certain compact car is normally distributed with a mean of 30 and a standard deviation of 1. What is the probability that the MPG for a randomly selected compact car would be less than 28?

The diameter of a brand of tennis balls is approximately normally distributed with a mean of 2.5 inches and a standard deviation of 0.5 inches.  A random sample of 50 ping-pong balls is selected.    What is the probability that the sample mean will be between 2.4 and 2.6 inches?

An engineer is going to redesign an ejection seat for an airplane. The seat was designed for pilots weighing between 130 lb and 181 lb. The new population of pilots has normally distributed weights with a mean of 136 lband a standard deviation of 29.6 lb. b. If 38 different pilots are randomly​ selected, find the probability that their mean weight is between 130 lb and 181 lb.

The diameter of a brand of ping-pong balls is approximately normally distributed with a mean of 1.5 inches and a standard deviation of 0.05 inches.  A random sample of 25 ping-pong balls is selected.    What is the probability that the sample mean will be between 1.48 and 1.52 inches?

The length of time on the SAT exam for a group of students is normally distributed with a mean of 2.5 hours and a standard deviation of 0.25 hours. A sample size of n= 60 is drawn randomly from the population. Find the probability that the sample mean is between two hours and three hours.