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Ice forms on a refrigerator ice-box at the rate of (4 – 06t)g per minute…

Ice forms on a refrigerator ice-box at the rate of (4 – 06t)g per minute after t minutes. If initially there are 2g of ice in the box, find the mass of ice formed in 5 minutes

  • A.
    19.5
  • B.
    17.0
  • C.
    14.5
  • D.
    12.5
Correct Answer: Option C
Explanation

(frac{dm}{dt}) = 4 – 0.6t
(int)dm = (int)(4 – 0.6t)dt
m = (4t – 0.3t^2 + c), when t = 0, m = 2g
∴ c = 2
m = (4t – 0.3t^2 + 2), when t = 5 minutes
m = (4(5) – 0.3(5)^2 + 2 = 20 – 7.5 + 2)
= 14.5

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