Title: Constant Rate of Change Post-Video Questions
Course: Calculus Videos Project > Section: Constant Rate of Change

Q: A candle has been burning at a constant rate of change of 2.25 inches per hour. The candle has been burning for 4 hours and is 4.5 inches tall. What was the length of the candle before it was lit?
- 4.5 inches
- 6.75 inches
- 9 inches
- 13.5 inches
- 20.25 inches
A: 13.5 inches

Q: When only half full, an Olympic sized swimming pool holds 330,000 gallons of water. Water is being pumped out of an Olympic pool at a constant rate. Every increase of five minutes in the number of minutes (x) since half full, the amount of water in the pool (y) decreases by 120 gallons.

Which of the following statements is definitely true? (Note: ∆y can be read as “change in y” and ∆x as “change in x.”)
- ∆x = –24∆y
- x = –24y
- y = –24x
- ∆y = –24∆x
- Only statements (a) and (b) are definitely true.
- Only statements (c) and (d) are definitely true.
A: ∆y = –24∆x