Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 7)
7.
A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?
8 hours
10 hours
12 hours
24 hours
Answer: Option
Explanation:

A's 1 hour's work = 1 ;
4

(B + C)'s 1 hour's work = 1 ;
3

(A + C)'s 1 hour's work = 1 .
2

(A + B + C)'s 1 hour's work = ( 1 + 1 ) = 7 .
4 3 12

B's 1 hour's work = ( 7 - 1 ) = 1 .
12 2 12

Therefore B alone will take 12 hours to do the work.

Discussion:
95 comments Page 1 of 10.

Lakshmi said:   5 months ago
A --->1/4.
A+B -->1/3.
(A+B)-A -->1/3-1/4.
= 1/12.
B alone 12 hours.
(8)

SUREKHA said:   5 months ago
A = 1/4
B + C = 1/3
A+C = 1/2
B =?

A + (B + C) - (A + C) = 1/4 + 1/3 - 1/2
B = 1/12.
B = 12 DAYS.
(9)

Kumar Pawar said:   6 months ago
A = 1/4 ---> (1)
B + C = 1/3 ---->(2)
A + C = 1/2---->(3)
Put Equation in (1)in (3)
A + C = 1/2.
1/4 + C = 1/2,
C = 1/2 - 1/4 = 1/4.
C = 1/4.
Put C in equation (2).
B + 1/4 = 1/3
B = 1/3 - 1/4
B = 1/12 Days.
So, the Answer is 12 days.
(6)

Moustafa Elhosiny said:   7 months ago
A's 1 hour = 1/4,
B+C 1 hour = 1/3,
A+C 1 hour = 1/2.

C = 1/2 - A
C = 1/2 - 1/4 = 1/4.
B+C = 1/3,
Then B = 1/3 -C.
B = 1/3 - 1/4 = 1/12.
So, B can do the work in 12 hours.
(6)

ARAVIND MATHALA said:   7 months ago
A = 1/4
B+C = 1/3
A+C = 1/2
B=?
C = (A+C)-A = > (1/2)-1/4 =>1/4,
B = (B+C)-C = >(1/3)-1/4 =>1/12.
Then B = 12 Hours.
(5)

NAVEEN CHIKATI said:   7 months ago
Hi,
A - 4.
B +C - 3.
A + C - 3.

LCM OF ALL -12
A = 12/4 = 3
B+C = 12/3 = 4
A+C = 12/2 = 6
B = ?.

TOTAL = (A) + (B+C) + (A+C),
= (3) + (4) + (6),
= 13.

TO FIND C= A + C = 6,
= 3 + c = 6,
C = 6 - 3,
C = 3.

TO FIND B = B + C = 4,
= B + 3 = 4,
B = 3 - 4,
B = 1.
B = 1/12.
B takes 12 hours.
(9)

Vijay said:   10 months ago
(B+C)-(A+C) = (B-A).
(B-A)+(A) = B.
1/3-1/2+1/4= 4/12 - 6/12 + 3/12 = 1/12.
= 12 hrs.
(6)

Hemaharshini said:   2 years ago
A = 1/4 ---(1)
B + C = 1/3 ----(2)
A + C = 1/2----(3)

=>Sub (1) in (3)
1/4 + C =1/2
C=1/4 => one day work of C---- (4)

=> Now sub (4) in (2) to find b's one day's work.
B + 1/4 = 1/3.
B = 1/12
B = 12 hours.
(37)

Jagadish Behera said:   2 years ago
DATA GIVEN:
A=4hrs
B+C=3hrs
A+C=2hrs.
B=?
Ans: Total work =12

A = 3work
B+C = 4work
A+C = 6work
A+C = 6.

3 + C = 6
C=6-3 = 3 WORK.

B+C=4
B=4-3=1

So, that B alone whole work in 12/1 = 12 hrs.
(53)

Dhananjay said:   2 years ago
A 1 hours work = 1/4 ----> (i)
B+C 1 hors work = 1/3 ----> (ii)
A+C 1 hour work = 1/2 ----> (iii).

By subtracting from (iii) to (ii) we get A-B = 1/6.
Now in place of A put the value of A = 1/4.
1/4-B = 1/6,
1/4-1/6 = B.
1/12 IS B'S 1 Hour's work.
B will take 12 hours.
(7)


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