Question

It takes two hours for two machines to manufacture 10000 parts. If machine #1 can do the job in one hour less than machine #2, how long does it take for each machine to manufacture 10000 parts alone

Answer 1

Answer:

Time machine one = 3.56

Time machine two = 4.56

Step-by-step explanation:

Let machine 2 do the job in x hours

Let machine 1 do the job in x - 1 hours.

The general formula for this problem is

Time = A*B/(A + B)

Givens

Time = 2 hours

B = x hours alone

A = x - 1 hours alone.

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x *( x - 1)

======= = 2

(x + x - 1)

(x^2 - x)/(2x - 1) = 2

x^2 - x = 2(2x - 1)

x^2 - x = 4x - 2

x^2 - 5x + 2 = 0

a = 1

b = - 5

c = 2

This gives 2 roots

x = 4.56

x = 0.43

The second root will not work because when 1 is subtracted from 0.43 the time give will be minus, which won't work.

Time for machine 2 is 4.56

The time for machine 1 is 3.56

Check

(A * B)/(A + B) = 2

A = 4.56

B = 3.56

Time = 4.56*3.56/(4.56 + 3.56)

Time = 16.2336/(8.12)

Time = 1.9992

The rounding error in the check comes from the rounding error in the times.