Suppose f(x) represents the total number of children that have bought a defective product, and x is the number of days since it came out.Step 2 of 2: Interpret the meaning of f'(42) = 12.12 is the rate of change in children who have bought a defective product after 42 days.12 is the total change between the first day and 42 days later.12 is the average change in the number of children who have bought a defective product between the first day and 42 days later.After 42 days 12 children have bought a defective product.