Question

At the moment a hot iron rod is plunged into freezing water, the difference between the rod's and the

water's temperatures is 100° Celsius. This causes the iron to cool and the temperature difference drops by
60% every second.
Write a function that gives the temperature difference in degrees Celsius, D(t), t seconds after the rod
was plunged into the water.​

Answer 1

D(t)=100(0.4)^t

Explanation:

Answer 2

The function is

`D(t) = 100 *( (40)/(100) )^(t)`

Explanation:

At t = 0 the difference is 100 degree celsius.

After one second the temperature difference will be
`100 - (100*60)/(100)` =
`100(1 - (60)/(100) )`

After two second, the difference will be
`100(1 - (60)/(100) )(1 - (60)/(100) ) = 100(1 - (60)/(100) )^(2)`

Hence, it can be written that,

`D(t) = 100 *(1 - (60)/(100) )^(t)` =
`100 *( (40)/(100) )^(t)`