Arithmetichard · Past Paper
If the ratios 5:x and y:20 are inverse to each other, then:
Axy = 100
Bx/y = 4
Cy/x = 4
Dxy = 1
✓ Correct Answer: A — xy = 100
Inverse of 5/x is x/5. So x/5 = y/20 => 20x = 5y => y = 4x. Wait, inverse to EACH OTHER. 5:x = 20:y. 5/x = 20/y => 5y = 20x => y=4x. Or (5/x)*(y/20)=1 => xy=100.
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