App Logo

No.1 PSC Learning App

1M+ Downloads
A is twice as good as a workman as B. And together, they finish a piece of work in 20 days. In how many days, will A alone finish the work?

A30 days

B25 days

C26 days

D28 days

Answer:

A. 30 days

Read Explanation:

Solution:

Given:

A = 2B

Concept used:

if A can do work in n days then one-day Work will be 1/n 

Calculation:

A is twice as good as B '

∴ time taken by A be x days and time taken by B be 2x days 

1/x + 1/2x = 1/20

2x+x2x2=120\frac{2x+x}{2x^2}=\frac{1}{20}

32x=120\frac{3}{2x}=\frac{1}{20}

2x=602x=60

x=30x=30

A alone finished work in 30 days


Shortcut Trick

 A is twice efficient as B 

∴ A = 2B 

⇒ A/B = 2/1

⇒ A + B = 3 

Total work = 20 × 3 = 60 

∴ A alone can finish work in = 60/2 = 30 days


Related Questions:

If 10 men can complete a piece of work in 12 days by working 7 hours a day, then in how many days can 14 men do the same work by working 6 hours a day?
A tank is filled in 4 hours by three pipes A, B and C. Pipe C is twice as fast as pipe B and pipe B is twice as fast as pipe A. How much time will pipe A take to fill the tank?
A യ്ക്ക് 15 ദിവസം കൊണ്ടും B യ്ക്ക് 20 ദിവസം കൊണ്ടും ഒരു ജോലി ചെയ്യാൻ കഴിയും. അവർ 4 ദിവസത്തേക്ക് ഒരുമിച്ച് ജോലി ചെയ്യുകയാണെങ്കിൽ, ശേഷിക്കുന്ന ജോലിയുടെ അംശം?
A man running at a speed of 15 km/hr crosses a bridge in 3 minutes. What is the length of the bridge?
18 ജോലിക്കാർ 5 ദിവസം കൊണ്ട് ചെയ്തു തീർക്കുന്ന ഒരു ജോലി 6 ദിവസം കൊണ്ടു ചെയ്തു തീർക്കാൻ എത്ര പേർ വേണം?