Machine B takes 7 minutes to cut 91 pieces of lumbers. Machine C takes 12 minutes to cut 120 pieces of lumbers. Machine D takes 9 minutes to cut 135 pieces of lumber.
- Which is the faster combination, B and C or C and D? (Eg A, B)
- In 1 minute, how many more pieces of lumbers can be cut by the faster combination compared to the other combination?
(a)
Time taken by Machine B alone:
7 min → 91 pieces
1 min → 91 ÷ 7 = 13 pieces
Time taken by Machine C alone:
12 min → 120 pieces
1 min → 120 ÷ 12 = 10 pieces
Time taken by Machine D alone:
9 min → 120 pieces
1 min → 135 ÷ 9 = 15 pieces
Time taken by Machine B and Machine C together:
1 min → 13 + 10 = 23 pieces
Time taken by Machine C and Machine D together:
1 min → 10 + 15 = 25 pieces
Machine C and D are the faster combination.
(b)
Number of more pieces of lumbers that can be cut by the faster combination (Machine C and D) in 1 minute
= 25 - 23
= 2
Answer(s): (a) C, D or D, C; (b) 2
