A does 80% of a work in 20 days. He then calls in B and they together…

Question

A does 80% of a work in 20 days. He then calls in B and they together finish the remaining work in 3 days. How long B alone would take to do the whole work?

Accepted Answer

Option C. 371/2 days. Answer & Solution Answer: Option C Solution: & Whole\, work\, is\, done\, by\, A\, in & = 20 × 5/4 = 25\, days & Now,\, ( 1 - 4/5 )\,\,i.e., & 1/5\, work\, is\, done\, by\, A\, and\, B\, in\, 3\, days & Whole\, work\, will\, be\, done\, by\, A\, and\, B\, in & = ( 3 × 5 ) = 15\,…