Aptitude - Time and Work - Discussion

A s 30% more eff...
i.e
A -> x(1+30/100) = 1/23
=> x(13/10) = 1/23
therefore
B -> x =10/299
add A+B u ll get 1/13
hence ans is 13

A can do a work in 100 days
B can do a work in 130 days, since A is 30% more efficient than B.
Take LCM of 100 & 130.i.e 1300
A's per day capacity = 1300/100 = 13
B's per day capacity = 1300/130 = 10

Given that A alone can do the given work in 23 days.
Therefore ,work completed by A alone in 23 days = 13 x 23 = 299
if they work together, their per day capacity = 13 + 10 = 23
both together will complete the given work in 299/23 = 13 days

Ans : 13 days

Here why dont we use shortcut formula (K*X)/{(k^2)-1}???.

Can any one clear my doubt??

A is 30% more efficient!!
So ratio will be 130:100 :: 23:x.
So x = 230/13
Final answer comes to 10.
Can someone plz confirm this?

Given that A is 30% efficient than B then

A=130% and b=100%
so 130%=23 days
then 100%=23*100/130=230/13
so B' 1 day work=13/230 and A' 1 day work=1/23
(A+B) one day work=(1/23+13/230)=10
so the answer is D

Hello its very easy ....
see
A is 30% more efficient than B
that means A=130% speed B=100% speed assume, then convert into ratio format because 13:10 it's work, now we can convert to days 10:13 (this ratio for separate man work days)

we must now ratio formula then only we understand
this method
A:B=A:B
also we write A:B::A:B

now apply
10:13::23:X ( Formula A:B::c:d =>A*d=B*c )

now we can solve that
10X=13*23
X=(13*23)/10
now we got X value X =299/10 days for B
B 1 day work is 299/10
then as usually go next steps

Thanks to Elumalai.

Say B does the work in x days.
A is 30% more efficient than B.

That means A will do it in x- (30*x/100) which is equal to 23 days.
So,

X-30*x/100=23.

70x=2300.

X=230/7.

So A and B together will work in.

[1/23+7/230]y=1.

Y=230/17=13.53=13 days (approx).

Chetan is right.

A requried to work is 23 days
A is 30% more efficient than B,that means B requried 30% more time than A
so,30% of A time= 23*30/100=6.9
so time requried for B=23+30% of A= 23+6.9=29.9
now,work per day for (A+B)=1/23+1/29.9 above work as per rule