1. A and B can separately do a piece of work in 20 and 15 days respectively. They worked together for 6 days after which B was replaced by C. The work was finished in next 4 days. The number of days in which C alone could do the work is :
Write Comment
Comments
By: anil on 05 May 2019 01.59 am
Work done by A in 1 day= = $$frac{1}{20}$$
Work done by B in 1 day= = $$frac{1}{15}$$
A and B worked together for 6 days.Work completed in 6 days =$$6(frac{1}{A} + frac{1}{B})$$
$$=6(frac{1}{20} + frac{1}{15}) = 6frac{7}{60} = frac{7}{10}$$
A and C worked together for next 4 days to complete the remaining $$frac{3}{10}$$ th of the work.
$$4(frac{1}{20} + frac{1}{C}) = frac{3}{10}$$
$$frac{1}{5} + frac{4}{C} = frac{3}{10}$$
$$frac{4}{C} = frac{3}{10} - frac{1}{5}$$
$$frac{4}{C} = frac{1}{10}$$
$$frac{1}{C} = frac{1}{40}$$
Hence C alone would take 40 days to complete the entire work.
Option D is the correct answer.
Terms And Service:We do not guarantee the accuracy of available data ..We Provide Information On Public Data.. Please consult an expert before using this data for commercial or personal use
Work done by B in 1 day= = $$frac{1}{15}$$
A and B worked together for 6 days.Work completed in 6 days =$$6(frac{1}{A} + frac{1}{B})$$
$$=6(frac{1}{20} + frac{1}{15}) = 6frac{7}{60} = frac{7}{10}$$
A and C worked together for next 4 days to complete the remaining $$frac{3}{10}$$ th of the work.
$$4(frac{1}{20} + frac{1}{C}) = frac{3}{10}$$
$$frac{1}{5} + frac{4}{C} = frac{3}{10}$$
$$frac{4}{C} = frac{3}{10} - frac{1}{5}$$
$$frac{4}{C} = frac{1}{10}$$
$$frac{1}{C} = frac{1}{40}$$
Hence C alone would take 40 days to complete the entire work.
Option D is the correct answer.