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A room has to be painted and worker A does 1/3 of the work then leaves. Next worker B does 1/4 of the remaining work and then leaves and finally worker C does 1/5 of the remaining work and then leaves.
What fraction of the room still needs to be painted?
a)3/5
b)2/5
c)13/60
d)7/15

Respuesta :

bangtanot7

Answer:

2/5, or B.

Explanation:

Let's make the total work needed x. Then Worker A does 1/3x and 2/3x work is left for the other workers to do (we know this because 1-1/3 = 2/3). Thus, worker B comes and does 1/4 of the remaining work, which is 2/3x. So, worker B does 1/4*(2/3x), which gives you 1/6x. Then, to find the work left over for worker C, we subtract 1/6x from 2/3x, which gives us 3/6x, or 1/2x. Then. worker C does 1/5 of 1/2x, giving us 1/5*(1/2x), which is 1/10x. To find the remaining work, we do 1/2x - 1/10x to get 4/10x, which simplifies to 2/5x. Therefore, the answer is 2/5, or B.

fichoh

Using the appropriate arithmetic operation, the fraction of the room which still needs to be painted is :2/5

Initial fraction = 1

Worker A : = 1/3

  • Fraction left = 1 - 1/3 = 2/3

Worker B : = 1/4

Fraction left = 2/3 - 1/4(2/3)

Fraction left = 2/3 - 1/6 = (4 - 1)/6 = 1/2

Worker C : = 1/5

Fraction left = 1/2 - 1/5(1/2)

Fraction left = 1/2 - 1/10 = (5 - 1)/10 = 4/10 = 2/5

Hence, the fraction of the room left to be painted is 2/5

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