JAMB 2013 · UTME · Q43

The mean of seven numbers is 10. If six of the numbers are 2, 4, 8, 14, 16 and 18, find the mode.

Worked solution (try it first)

Total of all seven numbers: $7 \times 10 = 70$ .
The six given add up to $2 + 4 + 8 + 14 + 16 + 18 = 62$ , so the seventh is $70 - 62 = 8$ .
Now 8 appears twice and every other number once, so the mode is 8, option D.