Copier F prints at a rate of 86 letters in every 2 minutes and Copier G prints at a rate of 120 letters in every 6 minutes. At 4 p.m., both copiers started printing. After a while, Copier F stopped printing for some time as the ink cartridges were being changed before it continued to print again. Copier G continued printing during this time. At 9 p.m., the total number of letters printed during the past five hours was 8557. Express the number of letters printed by Copier F 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 F prints per min = 86 ÷ 2 = 43
Number of letters Copier G prints per min = 120 ÷ 6 = 20

From 4 p.m. to 9 p.m. = 5 h
1 h = 60 min
5 h = 300 min

Number of letters printed by Copier G in 4 h
= 300 x 20
= 6000

Number of letters printed by Copier F in 4 h
= 8557 - 6000
= 2557

Percentage of the number of letters that Copier F printed over the total number of letters printed
= ²⁵⁵⁷₈₅₅₇ x 100%
≈ 29.88%

Answer(s): 29.88%