Prime numbers are numbers that has only two factors (i.e 1 and itself). They are numbers that are only divisible by 1 and their selves. First four Prime numbers greater than 10 are 11, 13, 17 and 19 Average = sum of numbers / number = \(frac{(11 + 13 + 17 + 19)}{4}\) = \(\frac{60}{4}\) = 15