algebra
posted by Kim .
John takes 3 hours longer than Andrew to peel 400 pounds of apples. Together they take 8 hours. How long will it take John to peel 400 pounds by himself

This should give you the information you need.
If it takes one person 5 hours to paint a room and another person 3 hours, how long will it take to paint the room working together?
Method 1:
1A can paint a room in 5 hours.
2B can paint a room in 3 hours.
3A's rate of painting is 1 room per A hours (5 hours) or 1/A (1/5) room/hour.
4B's rate of painting is 1 room per B hours (3 hours) or 1/B (1/3) room/hour.
5Their combined rate of painting is therefore 1/A + 1/B = (A+B)/AB = (1/5 + 1/3) = (8/15) rooms /hour.
6Therefore, the time required for both of them to paint the 1 room working together is 1 room/(A+B)/AB rooms/hour = AB/(A+B) = 5(3)/(5+3) = 15/8 hours = 1 hour52.5 minutes.
Note  Generally speaking (if the derivation is not specifically required), if it takes one person A units of time and another person B units of time to complete a specific task working alone, the time it takes them both to complete the task working together is T = AB/(A + B), where AB/(A + B) is one half the harmonic mean of the individual times, A and B.
You might like to derive the equivalant expression involving 3 people working alone and together which results in T = ABC/(AB + AC + BC).
Respond to this Question
Similar Questions

12th grade
it takes bill 4 hours to paint a house. it takes john 7 hours to paint the same house. how long does it take to paint the house if they painted it together. 
math
it takes bill 4 hours to paint a house. it takes john 7 hours to paint the same house. how long does it take to paint the house if they painted it together. 
algebra
it john 4 hours to mow a lawn it takes maria 3 hours to mow the same lawn, how long would it take if they worked together? 
algebra
Jonathan and Bill need to stack firewood. Jonathan can stack 130 pounds of firewood in 2 hours. Bill can stack 150 pounds of firewood in 3 hours. How long will it take them to stack 400 pounds of firewood if they work together (round … 
math
john takes 3hours longer than andrew to peel 400 pounds of apples. if together they can peel 400pounds of apples in 8hours then how long would it take john if he is working alone. 
Math
John takes 2 hours longer than Andrew to peel 400 pounds of apples. If together they can peel 400 pounds of apples in 7 hours, then how long would it take Andrew to peal the apples working alone? 
algebra
mary and jen peel 1lb of apple.if together they peeled 500 lbs of apple in 8 hours,then how long would it take each one working together? 
maths
For a certain amount of work,it takes john 6 hours less than tommy,if they both work together,it takes them 13 hours 20 minutes,how long will it take tommy alone to complete the work 
math
John can cut the grass in 4 hours working by himself. When john cuts the grass with his younger brother michael, it takes 3 hours. How long would it take michael to cut the grass by himself? 
Algebra
John can paint a house in 10 hours. Adam can paint the same house in 15 hours. A. Write an equation that can be used to find the time in hours, t, it would take John and Adam to paint the house together.