Problema Solution
A room needs to be painted. Bob can paint a room in 5 hours, while Nancy can paint one in 3 hours. If they both work together, how long will it take them to paint
the room?
Answer provided by our tutors
let
x = the time Bob and Nancy need to paint the room while working together
Bob paints the room alone in 5 hours, in 1 hour he will paint 1/5 of the room
Nancy paints the room alone in 3 hours, in 1 hour she will paint 1/3 of the room
Bob and Nancy working together in 1 hour will pain 1/x of the room
thus we can write
1/5 + 1/3 = 1/x
1/x = 8/15
x = 15/8 hours = 1.875 hours
x = 1 hour 52 min 30 sec
Bob and Nancy need 1 hour 52 min 30 sec or 1.875 hours to paint the room together.