Copier K prints at a rate of 105 letters in every 3 minutes and Copier L prints at a rate of 132 letters in every 6 minutes. At 3 p.m., both copiers started printing. After a while, Copier K stopped printing for some time as the ink cartridges were being changed before it continued to print again. Copier L continued printing during this time. At 5 p.m., the total number of letters printed during the past two hours was 8474. Express the number of letters printed by Copier K 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 K prints per min = 105 ÷ 3 = 35
Number of letters Copier L prints per min = 132 ÷ 6 = 22

From 3 p.m. to 5 p.m. = 2 h
1 h = 60 min
2 h = 120 min

Number of letters printed by Copier L in 3 h
= 120 x 22
= 2640

Number of letters printed by Copier K in 3 h
= 8474 - 2640
= 5834

Percentage of the number of letters that Copier K printed over the total number of letters printed
= ⁵⁸³⁴₈₄₇₄ x 100%
≈ 68.85%

Answer(s): 68.85%