Which situation represents direct proportion?

Which situation represents direct proportion?
  1. Number of workers and time taken to finish a fixed job
  2. Speed and time taken to cover a fixed distance
  3. Cost of pens and number of pens bought (same price each)
  4. Number of students sharing a fixed cake and slice size

Solution

Cost equals (number of pens) $\times$ (price per pen). With price fixed, cost varies directly with the number of pens.

Asked in: NTSE-F

Practice more DIRECT AND INVERSE PROPORTIONS questions on Aicharya