Engineering Board Exam Reviewer · Related Rates (Time Rates) · medium
A 25-ft ladder leans against a wall. The bottom is pulled away at 3 ft/s. Find the rate at which the top slides down when the bottom is 15 ft from the wall.
- 2.25 ft/s
- 2.0 ft/s
- 3.0 ft/s
- 1.8 ft/s
Answer
A. 2.25 ft/s
Solution
x2+y2=625. At x=15, y=20. Differentiating: dy/dt=-x/ydx/dt=-15(3)/20=-2.25 ft/s.
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