Correct Answer - Option 4 : 35
Given :
Mrinalini and Samyukta can paint half of the wall in 14 days
Mrinalini need 4 times more time than Samyukta
Concept used :
Working efficiency is inversely proportional to time taken
Total work = person's efficiency × Number of days he takes for work
Calculations :
Half the work will be completed in 14 days
Full work will be completed in 28 days
Total work = 28 units
Now,
Let the efficiency of Mrinalini be 'x' unit per day
So the efficiency of Samyukta will be '4x' per day
Mrinalini and Samyukta per day work = x + 4x = 5x units
So,
(5x) × 28 = 28 units
⇒ 5x = 28 /28
⇒ x = 1/5 units
Samyukta's per day work = 4x
⇒ 4 × (1/5) = 4/5 units
Total days of working of Samyukta = 28/(4/5)
⇒ 35 days
∴ Samyukta will complete the work in 35 days