# Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 21)

21.

A takes twice as much time as B or thrice as much time as C to finish a piece of work. Working together, they can finish the work in 2 days. B can do the work alone in:

Answer: Option

Explanation:

Suppose A, B and C take x, |
x |
and | x |
days respectively to finish the work. |

2 | 3 |

Then, | 1 | + | 2 | + | 3 | = | 1 | ||

x |
x |
x |
2 |

6 | = | 1 | |

x |
2 |

*x* = 12.

So, B takes (12/2) = 6 days to finish the work.

Discussion:

66 comments Page 1 of 7.
Karthick M said:
1 year ago

To simple method is:

A = 2B or A=3B

(A+B)'s 1day work = 1/2=(2B+B)'s 1day work

1/2 = 3B's 1-day work

ie, B's 1 day work = 1/6

So, B's whole work done is in 6 days.

A = 2B or A=3B

(A+B)'s 1day work = 1/2=(2B+B)'s 1day work

1/2 = 3B's 1-day work

ie, B's 1 day work = 1/6

So, B's whole work done is in 6 days.

(4)

Mahendra said:
2 years ago

Assume total work iso no of chairs from the give no of chair made per one day as per efficiency

A : B : C = 1 : 2 : 3.

So total chairs is 6 in one day.

Total days they together : 2 days.

So, total works = 6 * 2 = 12.

B alone can take = 12/2 = 6 days.

A : B : C = 1 : 2 : 3.

So total chairs is 6 in one day.

Total days they together : 2 days.

So, total works = 6 * 2 = 12.

B alone can take = 12/2 = 6 days.

(20)

Banjeet said:
3 years ago

A : B : C = 6 : 3 : 2,

11*2= 22 work,

So, B doing = (3/11) * 22 = 6 days.

11*2= 22 work,

So, B doing = (3/11) * 22 = 6 days.

(10)

Tyson said:
3 years ago

As the question says,

The time taken by A is twice that of B and thrice that of C, so

This means that;

Efficiency,

A=2*B=3*C

Efficiency is inversely proportional to the time taken to complete a task.

Time ratio

A/B=2/1,

A/C=3/1

So, the Efficiency ratio

A/B=1/2,

A/C=1/3

=>A/B/C=1/2/3.

A:B:C=1:2:3.

So in terms of RATIO,

Let 1-day work of A,B, C be 1unit, 2unit, 3unit.

i.e. work for A: 1 Day= 1 U---->eqn 1

work for B: 1 Day= 2 U----> eqn 2

Work for C: 1 Day= 3 U----eqn 3

Work for A+B+C: 1 Day= 6 U.

2 Day=12U----eqn iv

[Total work(12U) completes in Time =2days(given)

i.e.Total Works time taken by A+B+C, Time =2days]

Comparing (eqn ii & iv) find B can do the work alone

Work for B: 1 Day = 2 U ----> eqn 2

work for B: 3x2 Day = 6x2 U.

6 DAYS = 12 U.

B alone do the work in time = 6 days.

The time taken by A is twice that of B and thrice that of C, so

This means that;

Efficiency,

A=2*B=3*C

Efficiency is inversely proportional to the time taken to complete a task.

Time ratio

A/B=2/1,

A/C=3/1

So, the Efficiency ratio

A/B=1/2,

A/C=1/3

=>A/B/C=1/2/3.

A:B:C=1:2:3.

So in terms of RATIO,

Let 1-day work of A,B, C be 1unit, 2unit, 3unit.

i.e. work for A: 1 Day= 1 U---->eqn 1

work for B: 1 Day= 2 U----> eqn 2

Work for C: 1 Day= 3 U----eqn 3

Work for A+B+C: 1 Day= 6 U.

2 Day=12U----eqn iv

[Total work(12U) completes in Time =2days(given)

i.e.Total Works time taken by A+B+C, Time =2days]

Comparing (eqn ii & iv) find B can do the work alone

Work for B: 1 Day = 2 U ----> eqn 2

work for B: 3x2 Day = 6x2 U.

6 DAYS = 12 U.

B alone do the work in time = 6 days.

(1)

Abhishek said:
3 years ago

Let's assume.

C takes 4 days to do X work.

B takes 6 days for the same X work.

A takes 12 days for the same X work.

so, efficiency

A = 1/12.

B = 1/6.

c = 1/4.

So, as they all together takes 2 days to work,

x/(1/12)+(1/6)+(1/4) = 2

From that, we got X ( total work ) = 1

So time taken alone by;

B = 1/(1/) = 6 days.

C takes 4 days to do X work.

B takes 6 days for the same X work.

A takes 12 days for the same X work.

so, efficiency

A = 1/12.

B = 1/6.

c = 1/4.

So, as they all together takes 2 days to work,

x/(1/12)+(1/6)+(1/4) = 2

From that, we got X ( total work ) = 1

So time taken alone by;

B = 1/(1/) = 6 days.

Subhasish baul said:
4 years ago

A - 12.

B - 6.

C - 4.

Work as satisfied to take together 2day finished.

Efficiency A 1 B 2 C 3.

Total work 12.

Total efficiency 6.

Finished together 12 Ã· 6 = 2day satisfied

**B alone do in 12 Ã· 2 = 6 days.

B - 6.

C - 4.

Work as satisfied to take together 2day finished.

Efficiency A 1 B 2 C 3.

Total work 12.

Total efficiency 6.

Finished together 12 Ã· 6 = 2day satisfied

**B alone do in 12 Ã· 2 = 6 days.

Manohar said:
5 years ago

Simply:

6:3:1 = 9

9*2 = 18.

18/3 = 6.

6:3:1 = 9

9*2 = 18.

18/3 = 6.

(1)

Rajshekar said:
5 years ago

A x.

B 2x.

C 3x.

A+B+B = 1/2,

X+2x+3x = 1/2.

6x=1/2.

X=1/12.

So, be alone =2x = 2 * 1/12 = 1/6 = 6days.

B 2x.

C 3x.

A+B+B = 1/2,

X+2x+3x = 1/2.

6x=1/2.

X=1/12.

So, be alone =2x = 2 * 1/12 = 1/6 = 6days.

(3)

Rexi said:
5 years ago

Simply, it is solved by;

A=2B ; A=3C.

A/2=B ; A/3=C ---> time,

2/A=B; 3/A=C ---> efficiency,

1/A+2/A+3/A = 1/2 ---> A+B+C=1/2.

A = 12,

B = 6,

C = 4.

A=2B ; A=3C.

A/2=B ; A/3=C ---> time,

2/A=B; 3/A=C ---> efficiency,

1/A+2/A+3/A = 1/2 ---> A+B+C=1/2.

A = 12,

B = 6,

C = 4.

(3)

Aadhi said:
6 years ago

@Ajay.

How to find efficiency ratio?

How to find efficiency ratio?

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