When both printers M and N are used, a collection of books can be printed in 4 hours. While printing, Printer M broke down. As a result, it took 1
12 hours to complete printing. If it would take Printer N 6 hours to print the collection alone,
- How long would it take to print the collection of books using only Printer M? Express your answer in hours.
- How long was Printer M used before it broke down? Express your answer in hours.
(a)
Time taken by Printer M and N:
4 h → 1 collection of books
1 h → 1 ÷ 4 =
14 collection of books
Time taken by only Printer N:
6 h → 1 collection of books
1 h → 1 ÷ 6 =
16 collection of books
Time taken by only Printer M:
1 h →
14 -
16 =
112 collection of books
1 collection of books → 1 ÷
112 = 1 x 12 = 12 h
(b)
Time taken by only Printer N:
1
12 h → 1
12 x
16 =
14 collection of books
Fraction of the collection of books to be done by Printer M
= 1 -
14=
34 Time taken by Printer M before it broke down:
34 collection of books →
34 ÷
14 =
34 x
41 = 3 h
Answer(s): (a) 12 h; (b) 3 h