Copier C prints at a rate of 82 letters in every 2 minutes and Copier D prints at a rate of 129 letters in every 3 minutes. At 6 p.m., both copiers started printing. After a while, Copier C stopped printing for some time as the ink cartridges were being changed before it continued to print again. Copier D continued printing during this time. At 8 p.m., the total number of letters printed during the past two hours was 7947. Express the number of letters printed by Copier C 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 C prints per min = 82 ÷ 2 = 41
Number of letters Copier D prints per min = 129 ÷ 3 = 43

From 6 p.m. to 8 p.m. = 2 h
1 h = 60 min
2 h = 120 min

Number of letters printed by Copier D in 6 h
= 120 x 43
= 5160

Number of letters printed by Copier C in 6 h
= 7947 - 5160
= 2787

Percentage of the number of letters that Copier C printed over the total number of letters printed
= ²⁷⁸⁷₇₉₄₇ x 100%
≈ 35.07%

Answer(s): 35.07%