Please help me with this khan academy

Asmall book publisher knows that 26 books weigh 41 lbs. how much do 40 books weigh?

You use technology ans find a sum of 6.712e-8. write this sum in standard form

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $36.98. find the probability that a randomly selected bill will have an amount greater than $173, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?