boys from school A and 6 boysfrom school B together can set up an exhibition in 5 days, which 5 boys from school A and 10 boys
from school C together can do in 4 days or 3 boys from school B and 4 boysfrom school C together can do in 10 days. Then how
manyboys from schoolA can set up the exhibition in one day?
This questions was previously asked in
SSC CPO 9th Dec 2019 Shift-1
Explanation:
Let's assign work rates:
- Let 1 boy from school A = A's 1 day work
- 1 boy from school B = B
- 1 boy from school C = C
Let's set up equations based on the info:
- 4A + 6B = 1/5 (work/day as total work = 1, done in 5 days)
- 5A + 10C = 1/4
- 3B + 4C = 1/10
Let's solve:
1. From equation 2: 5A + 10C = 1/4 ? A + 2C = 1/20
2. From equation 3: 3B + 4C = 1/10
Now use values:
- From above, C = (1/20 - A)/2
- Substitute 3rd into 1st using C's value
- Also, from equation 1: 4A + 6B = 1/5 ? 2A + 3B = 1/10 ? 3B = 1/10 - 2A
But 3B + 4C = 1/10 so,
- (1/10 - 2A) + 4C = 1/10
- 4C = 2A
- C = A/2
Plugging back in A + 2C = 1/20
- A + 2(A/2) = 1/20 ? A + A = 1/20 ? 2A = 1/20 ? A = 1/40
So, 40 boys from school A can do the work in one day.
- Option 1: 80 (too many)
- Option 2: 40 (Correct)
- Option 3: 60 (not matching calculation)
- Option 4: 20 (too few)
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By: santosh