Question
A can complete a piece of work in 10 days. B in 15 days
and C in 20 days. A and C worked together for two days and then A was replaced by B. In how many days, altogether, was the work completed (in days)?Solution
Work done by ( A + C ) in 2 days = 2 (1/10 + 1/20 ) = 2 ((2 + 1)/20 ) = 6/20 = 3/10 Remaining work = 1 - 3/10 = 7/10 ( B + C )’s 1 day’s work = 1/15 + 1/20 = (4 + 3)/60 = 7/60 Time taken by ( B + C ) to finish 7/10 part of the work = 60/7 × 7/10 = 6 days Total time = 2 + 6 = 8 days Alternate method: Let total work = LCM (10,15,20) = 60 units So A’s 1 day work = 60/10 = 6 units B’s 1 day work = 60/15 = 4 units C’s 1 day work = 60/20 = 3 units A & C’s work for 2 days = (6+3)×2 = 18 units So remaining work = 60 – 18 = 42 units Now A is replaced by B So B & C together will do work in 1 day = 3 + 4 = 7 units So they can do the remaining job in = 42/ 7 = 6 days So total days = 6 + 2 = 8 days
Consider the following statements :
1.     A strait is a narrow passage of water between two landmasses.
2.     The shape of ...
The acronym UFFCCC stands forÂ
A city likely to record the lowest minimum annual temperature in July is
A tax payer pays Rs.2,10,000/- as income tax in a given year. If the rate of tax is nil on the first 2 lakh, 15% on the next 8 lakh and 25% on the rest,...
The Agasthyamalai Biosphere reserve is in:Â
Consider the following statements :
1.     All the megalithic (big stones) burials are underground.
2.     Sometimes, megalith...
The average of 10 numbers is 30. What will be the new average if one of the numbers is increased by 30 and five of the rest decreased by 4 each?
A cone is formed by rotating an equilateral triangle about its altitude. Fill in the blank.
Equilateral triangle : Cone = Square: ____
Who is the chairperson of 15th finance commissionÂ
How many times has the constitution been amended since its inception?