Mathematics - Ratios and Proportions - Direct and inverse proportion - Direct vs Inverse Proportion

6 steps: (1) DIRECT proportion: as one increases, the other increases at the same rate. More items = more cost. If 5 apples cost $10, then 10 apples cost $20. y = kx. (2) INVERSE proportion: as one increases, the other DECREASES. More workers = less time. If 4 workers take 6 hours, 8 workers take 3