Problema Solution
Jack, Kay, and Lynn deliver advertising flyers in a small town. If each person works alone, it takes Jack 2 h to deliver all the flyers, and it takes Lynn 1 h longer than it takes Kay. Working together, they can deliver all the flyers in 50% of the time it takes Kay working alone. How long does it take Kay to deliver all the flyers alone?
Answer provided by our tutors
so efficiency of jack =1/4
let the time taken by kay be x to deliver so efficiency of kay =1/x
so efficiency of lynn will be = 1/(9+x)
so total efficiency of both jack and lynn = 1/4 + 1/(9+x) = (13+x)/(4*(9+x))
so time taken to deliver = (36 + 4x)/(13+x)
which is half the time takn by kay
=>(36 + 4x)/(13+x) = x/2
=>72 + 8x = x^2 + 13x
=>x^2 + 5x -72 = 0
=>x = 6.5 approx