
Step-by-step explanation:

Let 
Then 
or

This gives us
or all integer multiples of 
Answer:
7 people, 7 walls, 48 minutes
Each person paints 1 wall in 48 minutes
20 persons, 20 walls
Each person can paint 1 wall in 48 minutes so it will take 48 minutes.
Answer:
95 intervals
Step-by-step explanation:
Given that
population mean = 100
standard deviation = 15
number of interval that involve the mean for 95% confidence interval is calculated as
We know that when we measure the 99 percent confidence interval, 99 outof 100 confidence interval are required to provide the mean population.
similarly
Assuming we measure a confidence interval of 95 percent, then we should expect 95 out of 100 confidence interval to provide the mean population therefore, answer is 95