Copier M prints at a rate of 84 letters in every 2 minutes and Copier N prints at a rate of 120 letters in every 5 minutes. At 2 p.m., both copiers started printing. After a while, Copier M stopped printing for some time as the ink cartridges were being changed before it continued to print again. Copier N continued printing during this time. At 6 p.m., the total number of letters printed during the past four hours was 8537. Express the number of letters printed by Copier M as a percentage of the total number of letters printed by both copiers. Round off your answer to 2 decimal places.
Number of letters Copier M prints per min = 84 ÷ 2 = 42
Number of letters Copier N prints per min = 120 ÷ 5 = 24

From 2 p.m. to 6 p.m. = 4 h
1 h = 60 min
4 h = 240 min

Number of letters printed by Copier N in 2 h
= 240 x 24
= 5760

Number of letters printed by Copier M in 2 h
= 8537 - 5760
= 2777

Percentage of the number of letters that Copier M printed over the total number of letters printed
= ²⁷⁷⁷₈₅₃₇ x 100%
≈ 32.53%

Answer(s): 32.53%