When both printers L and M are used, a collection of books can be printed in 3 hours. While printing, Printer L broke down. As a result, it took 4 hours to complete printing. If it would take Printer M 12 hours to print the collection alone,
- How long would it take to print the collection of books using only Printer L? Express your answer in hours.
- How long was Printer L used before it broke down? Express your answer in hours.
(a)
Time taken by Printer L and M:
3 h → 1 collection of books
1 h → 1 ÷ 3 =
13 collection of books
Time taken by only Printer M:
12 h → 1 collection of books
1 h → 1 ÷ 12 =
112 collection of books
Time taken by only Printer L:
1 h →
13 -
112 =
14 collection of books
1 collection of books → 1 ÷
14 = 1 x 4 = 4 h
(b)
Time taken by only Printer M:
4 h → 4 x
112 =
13 collection of books
Fraction of the collection of books to be done by Printer L
= 1 -
13=
23 Time taken by Printer L before it broke down:
23 collection of books →
23 ÷
13 =
23 x
31 = 2 h
Answer(s): (a) 4 h; (b) 2 h