A can lay railway track between two given station 20 days and B can do the same job in 16 days. With the help of C, they did the job in 8 days only. Then, C alone can do it job in:

Options
- 80 days
- 100 days
- 120 days
- 140 days

CORRECT ANSWER : 80 days

Discussion Board
easy way

a-20 days
b-16 days
a+b+c - 8 days
take lcm of 20,16,8 => 80 means total 80 units work
now a compl-> 4nits/day
b comp -> 5 units/day
a+b+c comp -> 10units/day

sub a, b value in a+b+c = 10
4+5+c = 10
9+c=10
c = 1 units/day
so o complete 80units works c take 80units*1unit/day == 80days


Sanjay Boga 10-16-2018 06:29 AM

work and time

A =1/20 (one day work)
B=1/16 (one day work)
A+B+C=1/8 (together one day work)
c=1/8-1/16-1/20
c=0.0125(one day work)
total time taken by c is 1/c=1/0.0125 (inverting principle)
c=80 days



dinesh battu 10-10-2018 06:25 AM

Write your comments


Enter the code shown above:

(Note: If you cannot read the numbers in the above image, reload the page to generate a new one.)


Advertisement
 
▲