In a large city it was found that summer electricity bills for single-family homes followed a normal distribution with a standard deviation of $100. A random sample of 25 bills was taken. a. Find the probability that the sample standard deviation is less than $75. b. Find the probability that the sample standard deviation is more than $150.

Find the mean and standard error of the mean of the sampling distribution. Then sketch a graph of the sampling distribution.   The prices of photo printers on a website are normally distributed with a mean of ​$238 and a standard deviation of ​$67. Random samples of size 33 are drawn from this population and the mean of each sample is determined.

Refer to the accompanying table, which describes results from groups of 8 births from 8 different sets of parents. The random variable x represents the number of girls among 8 children. Find the mean and standard deviation for the number of girls in 8 births. Click the icon to view the data table. The mean is u= girl(s). (Round to one decimal place as needed.) The standard deviation is o = e# girl(s). (Round to one decimal place as needed.) Table of numbers of girls and probabilities Number of Girls x 0 1 2 3 4 5 6 7 8 átv P(x) 0.004 0.034 0.117 0.218 0.278 0.217 0.102 0.027 0.003 D - X NiZ Next

Furnace repair bills are normally distributed with a mean of 271 dollars and a standard deviation of 20 dollars. If 64 of these repair bills are randomly selected, find the probability that they have a mean cost between 271 dollars and 273 dollars. Round to four decimal places. A. 0.2881 OB. 0.2119 O C. 0.5517 O D. 0.7881

Find the​ z-scores that correspond to each value and determine whether any of the values are unusual.

A survey finds that the prices paid for two-year-old Ford Fusion cars are normally distributed with a mean of $17,500.00 and a standard deviation of $500.00. Consider a sample of 10,000 people who bought two-year-old Ford Fusions. 6800 of the people who bought two-year old Ford Fusions spends between $ .00 and $ .00 How many people spends less than $17,000.00  people. How many people spends more than $19,000.00  people  (Note this question has to do with the empirical rule and the symmetric nature of the normal distribution)