Copier S prints at a rate of 80 letters in every 2 minutes and Copier T prints at a rate of 120 letters in every 4 minutes. At 4 p.m., both copiers started printing. After a while, Copier S stopped printing for some time as the ink cartridges were being changed before it continued to print again. Copier T continued printing during this time. At 6 p.m., the total number of letters printed during the past two hours was 7773. Express the number of letters printed by Copier S 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 S prints per min = 80 ÷ 2 = 40
Number of letters Copier T prints per min = 120 ÷ 4 = 30

From 4 p.m. to 6 p.m. = 2 h
1 h = 60 min
2 h = 120 min

Number of letters printed by Copier T in 4 h
= 120 x 30
= 3600

Number of letters printed by Copier S in 4 h
= 7773 - 3600
= 4173

Percentage of the number of letters that Copier S printed over the total number of letters printed
= ⁴¹⁷³₇₇₇₃ x 100%
≈ 53.69%

Answer(s): 53.69%