The letter series below is made by writing the same group of letters again and again.
R S R R T R S R R T R S R R T
If the series is continued in the same way, how many times will R appear in the first 52 letters?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 31
Count the letter in one full group, multiply by the number of full groups, then add the letters of the part-group at the end.
The repeating group is R S R R T (5 letters); it has 3 R’s
\(52 \div 5\) gives 10 full groups (50 letters) and 2 letters more
R’s in 10 full groups \(=10\times3=30\)
The 2 extra letters are R S, which have 1 R
Total \(=30+1=31\)