If 9 boy working 15/2 hours a day can finish a work in 20 days, then how many days will be taken by

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02 Dec 2015 Time and Work

If 9 boy working 15/2 hours a day can finish a work in 20 days, then how many days will be taken by 12 boy working 6 hours a day to finish the work, it being given than 3 boy of latter type work as much as 2 boy of he former type in the same.

OPtion

1) 19/2
2) 21/2
3) 17/2
4) 11
5) 15
6) 25/2
7) 27/2
8) 19
9) 9
10)13

Solution

More boy, less days (Direct)
Less hours a day, more days (Indirect)
More speed, less days (Indirect)
Men 12 : 9

Hr/day 6:15/2

Speed 1/2 : 1/3

:: 20 : x

x = 9* 15/2 * 1/3 * 20 * 1/12 * 1/6 * 2 = 25/2 days

Option 6)

Correct Option: 6 Best Solution (10)

MRITUNJAY   9 years AGO

B1/B2=3/2
so capacity are in ratio 3:2.
m1*d1*h1/c1=m2*d2*h2/c2
9*15*20/2*3=12*6*x/2

solve x=25/2

option 6

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ROHIT KUMAR DUBEY   9 years AGO

from formulae
M1*D1*T1/W2 =M2*D2*T2/W1.....(i)
also given
Efficiency 3boys of latter =2boys of former
i.e B2=3B1/2....(ii)
Put all value in eq(i)
9*7.5*20/1=(12*3B1/2 *6*X)/1......(let X is working day of 2nd type)
solving this X=25/2

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vishal varma   9 years AGO

we know that 3 boys latter can do work as much as 2 of former type therefore w2=(3/2)*w2
substitute in formula (m1 d1 h1)/w1 =(m2 d2 h2)/w2
9* 15/2 *20=3/2 * w2 *12*6
w2=25/2

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ABHINAV PUSHPAM   9 years AGO

capacity are in ratio
3:2.
m1*d1*h1/c1=m2*d2*h2/c2
9*15*20/2*3=12*6*x/2

solve x=25/2

option 6)

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Deepak kumar singh   9 years AGO

2/5, 3/5
9*15/2*2/5 men-hour completes in 20 days
=> 12*6*3/5 ,, ,, ,,
( 20*9*15/2*2/5)/(12*6*3/5)

=> 25/2 answer

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RAHUL KUMAR   9 years AGO

B1/B2=3/2
so, capacity are in ratio 3:2.

m1*d1*h1/c1=m2*d2*h2/c2

9*15*20/2*3=12*6*x/2

solve x=25/2

option (6) is correct ans.

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PRABHAT KUMAR   9 years AGO

A/c=(former type boy B1) /(latter type boy B2) =2/3
3(B1)=2(B2)
Now latter type 12 boy =formal type 8 boy
18()

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Devendra Marghade   9 years AGO

Former 9 boy's total work in hours=9*20*15/2=1350
If firmer boy's work=B1 & latter boy's work=B2, Given 2B1=3B2 or B1=3B2/2, So 12 B2's work=3*12/2=18 B1's work.
So days needed to complete the 1350 hr. of work by 12 latter type =18 former type=1350/(6*18)=25/2
Option 6)

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REYAZ FAHIM ANSARI   9 years AGO

according to chain rule
12*6*3*x=9*15/2*2*20
x=25/2

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harshavi   9 years AGO

we have the formula (m1*h1*d1/w1)=(m2*h2*d2/w2)
so we can say that 15*9*20/(2*b1)=12*6*d/(2/3*b1){since the work done by the latter type of 3 boys wold be equal to 2 boys of first type}
thus d=25/2

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