Q.1 A can do a piece of work in 5 days & B in 6 days & C in 12 days, then how long will they take all together ?

A) 2 2/9

B) 1 1/9

C) 3 3/9

D) 4 4/9

Ans. A

Shortcut:

(A+B+C) = xyz / xy + yz + zx

5 * 6 * 12 / 5*6 + 6*12 + 12*5

= 360 / 30+72+60

=2 2/9

Q.2 5 men can prepare 10 toys in 6 days working 6 hrs. Then in how many days can 12 men prepare 16 toys working 8 hrs a day ?

A) 3 days

B) 4 days

C) 5 days

D) 6 days

Ans. A

Shortcut:

M1D1W2T1 = M2D2T2W1

5*6*16*6 = 12 * D2*8*10

D2=5*6*16*6 / 12*10*8

= 3 days

Q.3 15 Men do ½ work in 20 days. In how many days will 20 men do the full work ?

A) 15 days

B) 40 days

C) 30 days

D) 20 days

Ans. C

Since, men & days are inversely proportional while work & days are directly proportional

i.e. 20 : 15 ? 20 : X

½ : 1

X = 15 * 1 * 20 / 20 * ½ = 30 days

Q.4 If 4 men or 7 women can finish a work in 60 days, in How many days same work can be finished by 8 men & 7 women ?

A) 18 days

B) 19 days

C) 20 days

D) 21 days

Ans. C

1/ 8/4*60 + 7/7*60

= 1/8/240 + 7/420

On solving

= 20

Q.5 A Contractor undertook to do work in 60 days. He employed 50 men. After 40 days he found that only half of the work had been done. How many additional men he should employ so that the work may be done in time ?

A) 50

B) 45

C) 40

D) 35

Ans. A

60 days – 40 days=20 days

Remaining work = 1-1/2 = ½

In 40 days, ½ work is done by the 50 men

Therefore, 50 * 40

In 20 days, 50*40/20 = 100

No. of additional men = 100-50 = 50