JAMB Mathematics 2023 Objective — Question 39
Question 39 of 40 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2023 Objective paper, with the correct answer and a full explanation.
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The radius r of a cylinder disc is increasing at the rate of 0.5cm/s. At what rate is the area of the disc increasing when its radius is 6cm?
- A. 36πcm²/s
- B. 3πcm²/s
- C. 18πcm²/s
- D. 6πcm²/sCorrect
Explanation
A=πr², dA/dt=2πr(dr/dt)=2π(6)(0.5)=6πcm²/s.
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