Practice Test 9

A city’s water utility began adding a corrosion-inhibiting compound to its water supply. After one year, the number of customer complaints about discolored tap water dropped by 40%. The utility concludes that the compound reduced corrosion in pipes and recommends continuing the treatment long-term. Which statement provides the strongest support for the conclusion?

A health clinic began sending text-message reminders to patients 24 hours before scheduled appointments. In the next quarter, the clinic’s no-show rate fell from 12% to 8%. The clinic manager concludes that text reminders reduce no-shows and recommends implementing the same reminder system for all clinics in the network. Which of the following, if true, most strengthens the argument?