# Ais twice as efficient as B.B started the work and after 4 days A joins B and the total work was complete in 9 days then B can complete whole work alo

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Ais twice as efficient as B.B started the work and after 4
days A joins B and the total work was complete in 9 days
then B can complete whole work alone in :
A. 9.5 days
B. 10 days
C. 19 days
D. 38 days

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A twice ecficient, so if B taken 2xdays to complete a
work, then A taken x days to complete that work.
Now, B worked for 9 days and A for (9 -4)= 5 days
S0,1/xx 5 + 1/(2x) xx 9 = 1
2x = 19
So, B is 19 days