A die is thrown three times and the sum of the three numbers is found to be 15. The probability that the first throw was a four is

In a given village there are only three sizes of families: families with 2 members, families with 4 members and families with 6 members. The proportion of families with 2,4 and 6 members are roughly equal. A poll is conducted in this village wherein a person is chosen at random and asked about his/her family size. The average family size computed by sampling 1000 such persons from the village would be closest to

The number of solutions (x, y, z) to the equation x – y – z = 25, where x, y, and z are positive integers such that x ? 40, y ? 12, and z ? 12 is

In how many ways can 7 identical erasers be distributed among 4 kids in such a way that each kid gets at least one eraser but nobody gets more than 3 erasers?