Question Bank

The cost $C$, in dollars, to remove $p$ percent of a certain contaminant from a reservoir is estimated by using the formula $C = \frac{20,000p}{100 - p}$. According to this estimate, how much more would it cost to remove 98 percent of the contaminant from the reservoir than it would cost to remove 75 percent of the contaminant?

At her regular hourly rate, Mira had estimated the labour cost of a repair job as $180, and she was paid that amount. However, the job took 6 hours longer than she had estimated and, consequently, she earned $5 per hour less than her regular hourly rate. What was the time Mira had estimated for the job, in hours?