The number of motorcycles sold annually by salespeople is normally distributed with a standard deviation of 15. A random sample of 300 salespeople taken and the mean number of motorcycles sold annually was found to be 75. Find the 99% confidence interval estimate of the population mean.

A successful basketball player has a height of 6 feet 11 ​inches, or 211 cm. Based on statistics from a data​ set, his height converts to the z score of 5.17. How many standard deviations is his height above the​ mean?

A community college Math instructor feels that the average age of community college students decreased since they started teaching 25 years ago.  Looking up data from the year the instructor started teaching, the mean age of community college students was 24.3 years old, with a population standard deviation of 2.2 years.  The Math instructor took a sample of 40 of their current community college students and found that the sample had a mean age of 23.7 years old.  Assume the population of ages of community college students is normally distributed and that the population standard deviation has remained the same. Test at the 5% significance level if the mean age of community college students is now less than 24.3 years old.   The question is attached.

Assume that the number of pieces per bag has a mean of 78 with a standard deviation of 1. use the empirical rule to find the percentage of values in the distribution between 78 and 79 and what’s the percentage above 79?

The Alpha company takes a survey of the age for all employees. The average age is 35 with a standard deviation of 3.2 years. The results for a normal distribution curve. If the company has 985 workers, how many are over 44 years old?

If the weight of fertilizer in a 40-pound bag is normally distributed with a standard deviation of 0.5 pounds, what is the range of weights of bags of fertilizer within two standard deviations of the mean?

A sociologist found that in a sample of 45 retired men, the average number of jobs they had during theirlifetimes was 7.2. The population standard deviation is 2.3(a) Find the best point estimate of the mean.The best point estimate of the mean is

A reading class can read an mean of 175 words per minute and a population standard deviation of 20 words per minutes.  The top 3% of the class is to receive a special award for a random sample of 49 students. What is the minimum average number of words per minute a student would need to read in order to get the award for a random sample of 49 students?  Assume the data is normally distributed.

A population of scores has a mean of 56. In this population, a raw score of 40 corresponds to a z score of -4. What is the population standard deviation?