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Maths Puzzle
Numerical Ability
Time and Work
To complete a task two men work on first day and three men work on second day and so on ,till it gets completed.If the same work can be completed by 9 mens for 15 days,in how many days will the work be completed in earlier case?
Read Solution (Total 8)
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- 54 days??
- 11 years agoHelpfull: Yes(2) No(1)
- work done by 9 men in 15 days will be 135 units.
it is said that
on 1st 2 men will work
on 2nd day 3 men will work
similarly on 3rd day 4men will work on so on..
all the work done by these men is same as 9 men
i.e
2*1+3*1+4*1+...n=135
adding 1 on both sides
1+2+3+4..n=135
n*(n+1)/2=135
n2+n-272=0
n2+17n-16n-272=0
n=16
so work will be completed in 16 days. - 9 years agoHelpfull: Yes(1) No(0)
- answer 15
2*1+3*1+4*1+...n=135
adding 1 on both sides
1+2+3+4..n=136
n*(n+1)/2=136
n2+n-272=0
n2+17n-16n-272=0
n=16
as 2 person worked on first day and 16 on last day
total no. of days is 15.
- 9 years agoHelpfull: Yes(1) No(0)
- ans = 15days
since, work of 9 men in 1 day => 9m=1/15
so, work of 1 man in 1 day => m=1/9*15
ATQ...
2*(1/9*15) + 3*(1/9*15) + 4*(1/9*15)+....+ upto nth term = 1 {total work}
=> 2 + 3 + 4 +.....+ upto nth term = 9*15
=>9*15 = n/2 (2*2 + (n-1)*d) {finding out the value of n(total days) by sum of nos. in A.P}
=>n^2+3n-270=0
=>(n+18)(n-15)=0
So, n=15days. - 9 years agoHelpfull: Yes(1) No(0)
- 18 days will be the answer
- 11 years agoHelpfull: Yes(0) No(1)
- Ans:54
9M takes 15days
1M takes 9*15 = 135 days
takes combination of 2M+3M= 5M= 2 days work
5M takes 135/5 = 27 days ( if 5M works on the same day )
if they divided into 2 groups no of days = 27*2 = 54 - 9 years agoHelpfull: Yes(0) No(0)
- 9 men=15 days
so ,1 man=135 days
or 135 man=1 day
2+3+4+5+.....=135
n/2{2*2+(n-1)*1}=135
n^2+3n-270=0
n^+18n-15n-270=0
n=15
Ans=15 - 9 years agoHelpfull: Yes(0) No(0)
- 9*15 = 135 DAYS.
2M+3M = 5M
135/5 = 27 DAYS.
M1*D1 = M2*D2
5*27 = 9*D
D = 15 DAYS - 8 years agoHelpfull: Yes(0) No(0)
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