Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 6)
6.
If 6 men and 8 boys can do a piece of work in 10 days while 26 men and 48 boys can do the same in 2 days, the time taken by 15 men and 20 boys in doing the same type of work will be:
4 days
5 days
6 days
7 days
Answer: Option
Explanation:

Let 1 man's 1 day's work = x and 1 boy's 1 day's work = y.

Then, 6x + 8y = 1 and 26x + 48y = 1 .
10 2

Solving these two equations, we get : x = 1 and y = 1 .
100 200

(15 men + 20 boy)'s 1 day's work = 15 + 20 = 1 .
100 200 4

15 men and 20 boys can do the work in 4 days.

Discussion:
201 comments Page 9 of 21.

Suji said:   1 decade ago
@Bavi.
Excellent trick.

@Sutha.
Multiply the term 1/10 also with 6(6/10=3/5).

Frank said:   1 decade ago
Where from the 1/4?

Esan said:   1 decade ago
What is wrong if I try to solve it like this:

6x+8y=10.
26x+48y=2.

Arrive at the value of x&y, then find 15x+20y to get the answer?

Can anyone explain? Thanks.

Anee said:   1 decade ago
2x+3y=10, 3x+2y=8, 2x+1y=?

Michelle said:   1 decade ago
I'm still confuse about how we got 1/100 and 1/200. I'm trying to figure out this problem from formula perspective (TIME X RATE = WORK).

However, it seems like everyone is just free styling with there methods to this question, I need structure.

Qasim said:   10 years ago
Hello to all I am confuse in x value.

6x+8y=1/10 ----- (i).
26x+48y=1/2 ------ (ii).

Multiply 1st equation into 6, then we get:

36x+48y=1/10*6.
26x+48y=1/2.

Change the sign of 2nd equation.

36x+48y=3/5.
-26x-48y=-1/2.

The result is:

10x=3/5-1/2.
10x=1/10.

Then,

x= 1/10/10= 10/1*10= 100/1=100.

Therefore x= 100.

Is it right please any one tell me.

And also tell me why in upward first solution there is x=1/100.

Bhargavi namballa said:   10 years ago
I didn't understand. Could you please explain once again?

S.Sabarish said:   10 years ago
Hello @Siddarth,

Your answers are extremely convincing. Please do give short cuts for other problems too.

Bikash Choudhury said:   10 years ago
It is simple method.

6m-----+8w-------- = 10.

6*10=60----8*10---- = 80....equation 1.

26m------+48w-------- = 2.

26*2=52------48*2=96....equation 2.

Equation 1- Equation 2.

60-52 = 8 and 96-80 = 16.

8:16 = 1:2.

12w+8w = 10.

=> 20w = 10.

=> 1w = 20*10.

We have to find 15m+20w = ?

=> 30w+20w = 50w = 200.

=> w = 200/50 = 4 days.

Divya said:   10 years ago
Please solve these equation i.e: 2x+3y = 1/10 and 3x+2y = 1/8.


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