Here's a 600-level work question I just made up. Working at the same constant rate, 4 machines, working together, take 8 days to make a total of 16 birdhouses. How many such machines are required to make 64 birdhouses in 16 days? A) 2 B) 4 C) 8 D) 16 E) 32 Answer: C

Working at the same constant rate, 4 machines, working together, take 8 days to make a total of 16 birdhouses. How many such machines are required to make 64 birdhouses in 16 days? A) 2 B) 4 C) 8 D) 16 E) 32 Answer: C One approach is to see what the original 4 machines can do in 16 days. 4 machines take 8 days to make 16 birdhouses. So, in 16 days, those same 4 machines can make 32 birdhouses So, if we add an additional 4 machines (that can also make 32 birdhouses in 16 days), the 8 combined machines will make 64 birdhouses in 16 days. Answer: C

Hi , In 1 day, 1 Machine can make = 16/8*4 = 1/2 right? so what will be next ? Please explain. Thanks

rsarashi wrote:Hi , In 1 day, 1 Machine can make = 16/8*4 = 1/2 right? so what will be next ? Please explain. Thanks That's correct; in 1 day, 1 machine can make 1/2 birdhouses So, in 2 days, 1 machine can make 1 birdhouse In 16 days, 1 machine can make 8 birdhouses So, in 16 days, 2 machines can make 16 birdhouses In 16 days, 4 machines can make 32 birdhouses In 16 days, 8 machines can make 64 birdhouses I could have skipped a few steps, but I think this might be clearer. Does that help? Cheers, Brent

That's correct; in 1 day, 1 machine can make 1/2 birdhouses So, in 2 days, 1 machine can make 1 birdhouse In 16 days, 1 machine can make 8 birdhouses So, in 16 days, 2 machines can make 16 birdhouses In 16 days, 4 machines can make 32 birdhouses In 16 days, 8 machines can make 64 birdhouses I could have skipped a few steps, but I think this might be clearer. Does that help? Hi Brent , Thanks for the explanation. All clear. Thanks, Rashi