Machine C takes 7 minutes to cut 70 pieces of lumbers. Machine D takes 14 minutes to cut 168 pieces of lumbers. Machine E takes 11 minutes to cut 143 pieces of lumber.
- Which is the faster combination, C and D or D and E? (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 C alone:
7 min → 70 pieces
1 min → 70 ÷ 7 = 10 pieces
Time taken by Machine D alone:
14 min → 168 pieces
1 min → 168 ÷ 14 = 12 pieces
Time taken by Machine E alone:
11 min → 168 pieces
1 min → 143 ÷ 11 = 13 pieces
Time taken by Machine C and Machine D together:
1 min → 10 + 12 = 22 pieces
Time taken by Machine D and Machine E together:
1 min → 12 + 13 = 25 pieces
Machine D and E are the faster combination.
(b)
Number of more pieces of lumbers that can be cut by the faster combination (Machine D and E) in 1 minute
= 25 - 22
= 3
Answer(s): (a) D, E or E, D; (b) 3