A researcher named liza wants to estimate the mean age of pilots in an airline company. The population standard deviation from the previous study is 6.30 years. How many pilots must be selected  if he wants to be 95% confident that the entire length of the interval must be 3.2 years

Hellen has just started a new years competition for her local climbing gym. There are two categories for this competition: singles and group (18 people). The rules are simple, put in the most hours in one months time and you get a guided tour to climb Ten Sleep canyon. She knows from running this competition over the years that the number of hours climbers at her gym spend training during this competiton is approximately normal and their mean competition hours per month in the gym are 24 hrs with a standard devaition of 6 hrs. Singles Distribution: X~N( , ) Group Distribution: x̄~N( , ) The winning single participant last year was in the 97 th percentile.... how many hours did the winner accumulate over the month?   One of Hellan's friends Dave put in 27.12 hours on the wall. What is the probablity that another individual will beat his time?   If someone puts in between 25.5-32.1 hours on the wall they get a Mountain Goat shirt. What percent of the singles competitors is expected to…

A population is normally distributed with a mean of 20.  What is the population standard deviation if you know 18% of the values are less than a value of 15

If someone scored a 17 when the mean is 19 with a SD of 5, what would their score be if the mean were 100 with a SD of 15?