Thomas takes 7 days to paint a house completely whereas raj requires 9 days to paint the same house completely. how many days will take to paint the house if both them work together ?



Thomas takes 7 days to paint a house completely whereas raj requires 9 days to paint the same house completely. how many days will take to paint the house if both them work together ?

A. 3

B. 5

C. 4

D. 8

Answer : C. 4


Explanation:

    No. of days taken by Thomas = 7 days.
    So work done by thomas in a day = 1/7

    No. of days taken by Raj = 9 days.
    Work done by other in a day = 1/9

    Work done by both in a day = 1/t

    1/7 + 1/9 = 1/t
    16/63 = 1/t.
    16t = 63.
    Days required by both (t) = 63/16.

    Total no. of days taken to paint the house is (approx.) = 4 days .


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