Stage Four

Problem No. 18 9s and 5 Dice

What is the likelihood of getting a total of 9 when rolling 5 dice?

CLUE: Think about how many combinations there are, and how many to get 9.

Chance and Data WM 3.2, WM 3.4

All Stage 4 Problems

Let's think about this.

How many combinations?

6 x 6 x 6 x 6 x 6 = 7776 possibilities

How many add up to 9? The best way to do this would be write a computer program that works out all these combination and counts the number that are equal to 9. Or do lots of trial and error.

Written in BASIC, a suitable program would be:

10 for A = 1 to 6

20 for B = 1 to 6

30 for C = 1 to 6

40 for D = 1 to 6

50 for E = 1 to 6

60 N = A+B+C+D+E

70 if N = 9 then T = T +1

80 next E

90 next D

100 next C

110 next B

1200 next A

130 print T

140 end

Give it a try if you have access to a computer running BASIC.