Working alone at its constant rate, machine K took 3 hours to produce ¼ of the units produced last Friday. Then machine M started working and the two machines, working simultaneously at their respective constant rates, took 6 hours to produce the rest of the unites produced last Friday. How many hours would it have taken machine M, working along at its constant rate, to produce all of the units produced last Friday?
Â
(A)Â 8
(B)Â Â 12
(C)Â 16
(D)Â 24
(E)Â Â 30
answer is D
My answer is D, 24 hours.
D – 24 hours
D
D
Answer is D
simple isnt it…
D
Option D
The correct answer is D.
Speed of machine K = A1/12 per hour
Speed of machine M = A1/24 per hour
d
Yes, D
BTW, could I put my question here? I dont know how to do
D. 24 hours.
Step 1: K completes F/4 in 3 hours. Therefore
K would complete F is 12 hours. Therefore
K completes 1/12 the job per hour.
Step 2: K + M complete 3F/4 in 6 hours. Therefore
K + M would complete F in 8 hours. Therefore
K + M would complete 1/8 the job per hour.
Step 3: K alone completes 1/12, or 2/24, of the job per hour.
K & M together complete 1/8, or 3/24, of the job per hour.
M alone therefore completes 3/24 – 2/24 = 1/24 of the job per hour.
Conclusion: It takes M alone 24 hours to complete the job.
D