A recent survey was taken to determine the cost of gas energy. Results of the survey revealed that the

The average monthly utility bill of a three-bedroom house using gas was $125 and the standard deviation was $15.

If nothing is known about the distribution of utility bills, what can you say about the fraction of all three-bedroom homes that have gas bills between $80 and $170?

If it can be assumed that the distribution of utility bills is mound-shaped, approximately what proportion of three-bedroom homes would have monthly bills less than $110?