JAMB 2003 · UME · Q46

The result of tossing a fair die 120 times is summarized below. Find the value of $x$ .

Number	1	2	3	4	5	6
Frequency	12	20	$x$	21	$x - 1$	28

Worked solution (try it first)

The frequencies add up to the 120 tosses: $12 + 20 + x + 21 + (x - 1) + 28 = 120$ .
Collect terms: $80 + 2x = 120$ , so $2x = 40$ .
So $x = 20$ , option D.