Bill, bob, and barry are hired to paint signs. in 8 hours bill can paint 1 sign, bob can paint 2 signs, and barry can paint 1 and 1 / 3 signs. they all come to work the first day, but barry doesn't like the job and quits after 3 hours. bob works half an hour longer than barry and quits. how long will it take bill to finish 2 signs they were supposed to paint?

Question

Mathematics

Kylie Jimenez

24 December, 10:01

Bill, bob, and barry are hired to paint signs. in 8 hours bill can paint 1 sign, bob can paint 2 signs, and barry can paint 1 and 1 / 3 signs. they all come to work the first day, but barry doesn't like the job and quits after 3 hours. bob works half an hour longer than barry and quits. how long will it take bill to finish 2 signs they were supposed to paint?

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Answers (1)

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Leandro Esparza · Answer 1

Define rates at which the individuals paint.

Bill: x = 1/8 signs/h

Bob: y = (2 signs) / (8 h) = 1/4 signs/h

Barry: z = (4/3 signs) / (8 h) = 1/6 signs/h

The job is to paint 2 signs, working together.

In the first 3 hours, the amount painted is

(x+y+z signs/h) * (3 h) = (1/8 + 1/4 + 1/6) * 3 = 13/8 signs

Remaining: 2 - 13/8 = 3/8 signs

Barry quits.

In the next 1/2 hour (30 minutes), the amount painted is

(x + y signs/h) * (0.5 h) = (1/8 + 1/4) * 0.5 = 3/16 signs

Remaining: 3/8 - 3/16 = 3/16 signs

Now Bob quits.

The time for Bill to finish the job is

(3/16 signs) / (1/8 signs/h) = 3/2 h

Answer: Bill finishes the job in 1.5 hours (or 1 hour, 30 minutes)