When both printers N and P are used, a collection of books can be printed in 2 hours. While printing, Printer N broke down. As a result, it took 1
12 hours to complete printing. If it would take Printer P 3 hours to print the collection alone,
- How long would it take to print the collection of books using only Printer N? Express your answer in hours.
- How long was Printer N used before it broke down? Express your answer in hours.
(a)
Time taken by Printer N and P:
2 h → 1 collection of books
1 h → 1 ÷ 2 =
12 collection of books
Time taken by only Printer P:
3 h → 1 collection of books
1 h → 1 ÷ 3 =
13 collection of books
Time taken by only Printer N:
1 h →
12 -
13 =
16 collection of books
1 collection of books → 1 ÷
16 = 1 x 6 = 6 h
(b)
Time taken by only Printer P:
1
12 h → 1
12 x
13 =
12 collection of books
Fraction of the collection of books to be done by Printer N
= 1 -
12=
12 Time taken by Printer N before it broke down:
12 collection of books →
12 ÷
12 =
12 x
21 = 1 h
Answer(s): (a) 6 h; (b) 1 h