In 5 letters of the word ROLLS, the letter L comes two times.
Total permutations = \(\frac{5!}{2!}=\frac{120}{2}\) = 60
In 5 letters of the word DOLLS, the letter L comes two times
Total permutations = \(\frac{5!}{2!}=\frac{120}{2}\) = 60
∴ The ratio of number of arrangements of all the letters of the word ROLLS and
DOLLS = 60 / 60 = 1 / 1 = 1 : 1