Elitmus
Exam
obama is a creator and osama is a destroyer. if obama dis any work in 21 months and osama did it in 28 months. in how many months they did the work complete if they are working alternatively.
Read Solution (Total 5)
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- 161 months
creator 1/21 of a building in a month
destroyer 1/28 of a building in a month
in two months (1/21)-(1/28)=1/84
in one month building completed = 1/168
They are working alternatively so first creator creates a building and the destroyer destroys it in the next month)
If building completed in 1 month = 1/168
then in 160 month building completed = 160/168
now the 161 month is creators turn so 160/168 + 1/21=168/168
Hence in the 161 month building will be completed. - 11 years agoHelpfull: Yes(38) No(2)
- ans 161
a works 588/21=28unit/month - 11 years agoHelpfull: Yes(4) No(2)
- 168 months
- 11 years agoHelpfull: Yes(1) No(3)
- Let total work=84 units (lcm of 21 and 28)
So obama works or creates = 84/21=4 units per month,
and osama works or destroys= 84/28=-3 units per month.(osama is destroyer so negative sign taken.)
So net work will be = 4-3=1.
- 11 years agoHelpfull: Yes(0) No(4)
- 168 months
- 10 years agoHelpfull: Yes(0) No(0)
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