Question
'Preeti' can complete a piece of work in 70 days, while
'Bhanumati' can complete it in 90 days. They both started the work together, but 'Preeti' left after 23 days. 'Bhanumati,' with the assistance of 'Chirag,' completed the remaining work in 21(5/6) days. Calculate the time required for 'Chirag' to complete the entire work on his own.Solution
ATQ, Let total amount of work = 630 units (LCM of 90 and 70) Efficiency of ‘Preeti’ = 630/70 = 9 units per day Efficiency of ‘Bhanumati’ = 630/90 = 7 units per day Amount of work completed by ‘Preeti’ and ‘Bhanumati’ together in 23 days = 16 × 23 = 368 units Remaining work = 630 – 368 = 262 units Efficiency of ‘Bhanumati’ and ‘Chirag’ together = 262/(131/6) = 12 units per days So, efficiency of ‘Chirag’ = 12 – 7 = 5 units per day Hence required time = 630/5 = 126 days
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