Workload-2

Algebra Level 3

Two women and five men can finish a piece of embroidery in four days, while three women and six men can do the same work in three days. Find the number of days one woman takes to finish the embroidery.


The answer is 18.

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2 solutions

Chew-Seong Cheong
Aug 17, 2016

Let the rate of completing a piece of embroidery W W by one woman be x x . That is if it takes n n days for a woman to complete W W , then we have n x = W nx = W . Similarly, let the rate of completing W W by one man be y y . Then we have:

{ 4 ( 2 x + 5 y ) = 8 x + 20 y = W . . . ( 1 ) 3 ( 3 x + 6 y ) = 9 x + 18 y = W . . . ( 2 ) \begin{cases} 4(2x+5y) = 8x + 20y = W &...(1) \\ 3(3x+6y) = 9x+18y = W &...(2) \end{cases}

( 2 ) × 10 9 : 10 x + 20 y = 10 9 W . . . ( 2 a ) ( 2 a ) ( 1 ) : 2 x = 1 9 W 18 x = W \begin{aligned} (2) \times \frac {10}9: \quad 10x + 20y & = \frac {10}9 W & ...(2a) \\ (2a)-(1): \quad 2x & = \frac 19 W \\ \implies \boxed{18}x & = W \end{aligned}

Therefore, the number of days one women takes to complete the embroidery is 18 \boxed{18} .

Did similarly, got your two equations, but then equated the LHS's:

8x + 20y = 9x + 18y

2y = x

y = 0.5x ... (3)

Substituting (3) into (1):

W = 8x + 20 × 0.5x = 18x

Zee Ell - 4 years, 10 months ago

Given 2w+5m in 1 day can complete 1/4th ( eq.1) and 3w+6m in 1 day can complete 1/3rd of the project ( eq.2) From eq1, 1w+2.5m in 1 day can complete 1/8th and from eq2-eq1, 1w+1m can complete 1/12th in one day. From 1w+2.5m=1/8 and 1w+1m=1/12, Multiply 2.5 to 1w+1m=1/12 and we get 2.5w+2.5m=5/24 (eq4) Take eq4-eq1 and we get 1.5w=5/24-1/8=1/12 Hence, 1 woman in 1 day can complete 1/12*2/3 or 1/18th of the project. To complete the entire project by herself, it will take 18 days!

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