The average of three-digit numbers 432, 407, x32, 4x1, 38x is 508.  Then find the average of x+1, x-2, x+3, x+2.

9 4 3 5

9

Take unit digit of all numbers. 2 + 7 + 2 + 1 + x = 8 × 5              (Total = 508 × 5) 12 + x = 0    →     (unit digit of 8 × 5 = 40)  Now, x = 8 So, 12 + 8 = 0 ⇒ \(\frac{8+1+8-2+8+3+8+2}{4}\) = \(\frac{36}{4}\) = 9