When both printers Z and A are used, a collection of books can be printed in 6 hours. While printing, Printer Z broke down. As a result, it took 7
12 hours to complete printing. If it would take Printer A 15 hours to print the collection alone,
- How long would it take to print the collection of books using only Printer Z? Express your answer in hours.
- How long was Printer Z used before it broke down? Express your answer in hours.
(a)
Time taken by Printer Z and A:
6 h → 1 collection of books
1 h → 1 ÷ 6 =
16 collection of books
Time taken by only Printer A:
15 h → 1 collection of books
1 h → 1 ÷ 15 =
115 collection of books
Time taken by only Printer Z:
1 h →
16 -
115 =
110 collection of books
1 collection of books → 1 ÷
110 = 1 x 10 = 10 h
(b)
Time taken by only Printer A:
7
12 h → 7
12 x
115 =
12 collection of books
Fraction of the collection of books to be done by Printer Z
= 1 -
12=
12 Time taken by Printer Z before it broke down:
12 collection of books →
12 ÷
16 =
12 x
61 = 3 h
Answer(s): (a) 10 h; (b) 3 h