Quantitative Aptitude – Arithmetic – Time and Work – Humans and robots can both perform

Slot -1 – Quantitative Aptitude – Arithmetic – Time and Work – Humans and robots can both perform

Humans and robots can both perform a job but at different efficiencies. Fifteen humans and five robots working together take thirty days to finish the job, whereas five humans and fifteen robots working together take sixty days to finish it. How many days will fifteen humans working together (without any robot) take to finish it?

a) 36
b) 40
c) 45
d) 32

Answer: d) 32

Solution:

Given, 15/H+5/R=1/30  ——-1)
And 5/H+15/R=1/60  ——–2)

By solving eq 1) & eq 2) we get
1/(H )=1/(40×12)

Thus H = 40×12
So time taken by 15 humans = 40×12/15=32

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