43 Views

Question : Two persons A and B working separately can sanitise a building in 6 hours and 10 hours, respectively. They work in stretches of one hour alternately. If A begins at 8 a.m., then when will the work be finished?

Option 1: $9\frac{1}{3}$ h

Option 2: $7\frac{1}{3}$ h

Option 3: $6\frac{1}{3}$ h

Option 4: $8\frac{1}{3}$ h


Team Careers360 24th Jan, 2024
Answer (1)
Team Careers360 25th Jan, 2024

Correct Answer: $7\frac{1}{3}$ h


Solution : Person A can sanitise a building in 6 hrs.
Person B can sanitise a building in 10 hrs.
Total work = Efficiency$\times$Times
Let the total work = LCM of 6 and 10 = 30 units
Efficiency of A = $\frac{30}{6}$ = 5 units
Efficiency of B = $\frac{30}{10}$ = 3 units
According to the question,
(5+3) = 8 units of work done in 2 hours 
​​​​​So, in 6 hours work done = $8\times\frac{6}{2} = 24$ units
Till 7th hour, work completed = 24 + 5 = 29 units
Remaining work = 30 – 29 = 1 unit
1 unit of work is completed by B in $\frac{1}{3}\ \mathrm{hour}$
Total time is taken to complete the total work = $7\frac{1}{3}$ h
Hence, the correct answer is $7\frac{1}{3}$ h.

SSC CGL Complete Guide

Candidates can download this ebook to know all about SSC CGL.

Download EBook

Know More About

Related Questions

Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books