1) It has been found that times taken by people to complete a particular tax form follow a normal distribution with a mean of 100 minutes and a standard deviation of 30 minutes. A random sample of nine people who have completed this tax form was taken. a) What is the probability that the sample mean time taken is less than 85 minutes? b) The probability is 0.01 that the sample standard deviation of time taken is less than how many minutes?

Suppose that the commuting time on a particular train is uniformly distributed between 35 and 55 minutes. What is the standard deviation of the commuting time?

Suppose the mean income of firms in the industry for a year is 25 million dollars with a standard deviation of 9 million dollars. If incomes for the industry are distributed normally, what is the probability that a randomly selected firm will earn between 36 and 42 million dollars? Round your answer to four decimal places.

Suppose the mean income of firms in the industry for a year is 2525 million dollars with a standard deviation of 77 million dollars. If incomes for the industry are distributed normally, what is the probability that a randomly selected firm will earn less than 4040 million dollars? Round your answer to four decimal places.

Assume that adults have IQ scores that are normally distributed with a mean of95.4 and a standard deviation of 16.6. Find the probability that a randomly selected adult has an IQ greater than 118.1 The probability that a randomly selected adult from this group has an IQ greater than 118.1 is what?

It has been found that times taken by people to complete a particular tax form follow a normal distribution with a mean of 100 minutes and a standard deviation of 30 minutes. A random sample of nine people who have completed this tax form was taken. a. What is the probability that the sample mean time taken is more than 120 minutes? b. The probability is 0.20 that the sample mean time taken is less than how many minutes? c. The probability is 0.05 that the sample standard deviation of time taken is less than how many minutes?

1. Assume that IQ are normally distributed with a mean of 100 and standard deviation of 15. For a sample of 25 adults, find the probability that their mean IQ score will be greater than 90?

Suppose IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability a random sample of 250 people has a mean IQ of more than 102?

a) Attendance at large exhibition shows in Denver averages about 8000 people per day, with standard deviation of about 475. Assume that the daily attendance figures follow a normal distribution. (Round your answers to four decimal places.)  What is the probability that the daily attendance will be fewer than 7200 people? What is the probability that the daily attendance will be more than 8900 people? What is the probability that the daily attendance will be between 7200 and 8900 people?   b) Most exhibition shows open in the morning and close in the late evening. A study of Saturday arrival times showed that the average arrival time was 3 hours and 48 minutes after the doors opened, and the standard deviation was estimated at about 56 minutes. Assume that the arrival times follow a normal distribution.    At what time after the doors open will 92% of the people who are coming to the Saturday show have arrived? (Round your answer to the nearest number of minutes.) ____minutes after…