fast pump takes x hour
Slow pump takes 1.5x hour
1/x + 1/1.5x = 1/4
1/x = 1/4 - 1/1.5x
1/x = (1.5x - 4)/6x
6x = 1.5x^2 - 4x
10x = 1.5x^2
10 = 1.5x
x = 10/1.5 --> stop here during practice exam because it seems strange and you have a serious lack of confidence
x = 20/3
can somebody confirm please ??
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Slow pump takes 1.5x hour
1/x + 1/1.5x = 1/4
1/x = 1/4 - 1/1.5x
1/x = (1.5x - 4)/6x
6x = 1.5x^2 - 4x
10x = 1.5x^2
10 = 1.5x
x = 10/1.5 --> stop here during practice exam because it seems strange and you have a serious lack of confidence

x = 20/3
can somebody confirm please ??


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