June 2006 C3 Past Paper Question :S

Meggggggggaaaa confused!!!

here is the question:

A heated metal ball is dropped into a liquid. As the ball cools, its temperature, T °C,
t minutes after it enters the liquid, is given by
T = 400 e–0.05t + 25, t �� 0.
(a) Find the temperature of the ball as it enters the liquid.
(1)
(b) Find the value of t for which T = 300, giving your answer to 3 significant figures.
(4)
(c) Find the rate at which the temperature of the ball is decreasing at the instant when
t = 50. Give your answer in °C per minute to 3 significant figures.
(3)(d) From the equation for temperature T in terms of t, given above, explain why the
temperature of the ball can never fall to 20 °C.
(1)


if anyone can understand this and get the right answer i will be eternally grateful as have done the question but seem to be unable to get the right answer

b) Substitute T=300 into the given equation.
c) Differentiate and find $\frac{dT}{dt}$

Meggggggggaaaa confused!!!

here is the question:

A heated metal ball is dropped into a liquid. As the ball cools, its temperature, T °C,
t minutes after it enters the liquid, is given by
T = 400 e–0.05t + 25, t 􀀮 0.
(a) Find the temperature of the ball as it enters the liquid.
(1)
(b) Find the value of t for which T = 300, giving your answer to 3 significant figures.
(4)
(c) Find the rate at which the temperature of the ball is decreasing at the instant when
t = 50. Give your answer in °C per minute to 3 significant figures.
(3)(d) From the equation for temperature T in terms of t, given above, explain why the
temperature of the ball can never fall to 20 °C.
(1)


if anyone can understand this and get the right answer i will be eternally grateful as have done the question but seem to be unable to get the right answer

can someone post how you actually do part c please so confused but i have done a and b