Question

If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

• A. 2 hours and 24 minutes
• B. 3 hours and 12 minutes
• C. 3 hours and 44 minutes
• D. 4 hours and 10 minutes
• E. 4 hours and 33 minutes

Answer 1

The correct option is A 2 hours and 24 minutes

• In $1$ hour , sally can paint $1/4$ th house
• In $1$ hour , john can paint $1/6$ th house
• In $1$ hour they both combined can paint $1/4+1/6=5/12$ th house
• So they both combined can paint the house in $12/5$ hour which implies $2$ hours and $24$minutes