PSLE Letters R, B, T formed a patten as shown below.
R B R T R R B R T R R B R T R . . .
If there are 52 'R', what is the greatest possible number of letters in the pattern?
Number of letters in 1 set of R B R T R = 5
Number of letters 'R' in 1 set of R B R T R = 3
Number of sets of 3 'R' if there are 52 'R'
= 52 ÷ 3
= 17 r 1
If the remainder is 1, there is 1 'R' and the largest possible number of letters is the final incomplete set is 2. (R B)
If the remainder is 2, there are 2 'R' and the largest possible number of letters is the final incomplete set is 4. (R B R T)
Greatest possible number of letters
= 17 x 5 + 2
= 85 + 2
= 87
Answer(s): 87