During the year of 2001, in the US residential lenders were saturated in refinancing. The total mortgage packages approved exceeded $1.5 trillion. However, refinancing was not homogeneous across the US. Twenty major mortgage institutions were randomly selected, and...

According to an IRS study, it takes an average of 330 minutes for taxpayers to prepare, copy, and electronically file a 1040 tax form. A consumer watchdog agency selects a random sample of 40 taxpayers and finds the standard deviation of the time to prepare, copy, and...

Let x be a random variable that represents the length of time it takes a student to complete Dr. Tracy Wang’s homework. From long experience, it is known that x has a normal distribution with mean hours and standard deviation hour. Convert each of the following...

The length of human pregnancies from conception to birth varies according to a distribution that is approximately normal with mean 266 days and standard deviation 16 days. a) What percent of pregnancies last less than 240 days (about 8 months)? b) What percent of...

The volumes of soda in quart soda bottles are normally distributed with a mean of 32.3 oz and a standard deviation of 1.2 oz. What is the probability that the volume of soda in a randomly selected bottle will be less than 32 oz? Solution: Letbe the random volume of...