Jake makes a list of all the four-digit positive integers with the property that the product of the four digits is 5. What is the arithmetic mean of the integers on his list?

The only factors (divisors) of 5 are 1 and 5

So....

The only way this is possible is if we have the following integers:

1115

1151

1511

5111

The mean = 8888/4 = 2222

Thanks!