If 25 typists can type 60 letters in 20 minutes, then how many letters will 75 typists working at the same rate complete in 1 hour?	Select the correct option
A) 270  B) 540  C) 610  D) 510  E) 500

Rationale: no . of letters typing by 25 typists in 20 minutes = 60 no . of letters typing by 25 typists in 60 minutes = 60 * 3 = 180 no . of letters typing by 75 typists in 60 minutes = 180 / 25 * 75 = 540 answer : b
Answer: B