ASVAB Practice Math Questions

Category - Math - Hard

Three machines, individually, can do a certain job in 2, 3 and 4 hours, respectively. What is the greatest part of the job that can be done in one hour by two of the machines working together at their respective rates?
  1. 13/12
  2. ¾
  3. 5/6
  4. 6/5
Explanation
Answer C The greatest part of the job that can be done in one hour by the two fastest of the three machines i.e. by first two machines.
In 1 hr the first machine does ½ work and the second machine does 1/3 work.
So in hour both machines working together do ½ + 1/3 = 5/6 works

Key takeaway: In the questions based on time and work, take the total work to be done as one unit of work. Remember the basic concept that if A does a work in x hour , the in one hour A does 1/x of the work in 1 hour.
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