Answer:
a) [tex]y(t) = 30 + 25t[/tex]
b) The pollution level at 4 o'clock in the afternoon is of 280 parts per million.
Step-by-step explanation:
The pollution level in the center of a city at 6 am is 30 parts per million and it grows in linear fashion by 25 parts per million every hour.
This means that the pollution in t hours after 6 am is given by:
[tex]y(t) = 30 + 25t[/tex], which is the answer to question a.
b. The pollution level at 4 o'clock in the afternoon
4 in the afternoon is 10 hours after 6 am, so this is y(10).
[tex]y(10) = 30 + 25*10 = 30 + 250 = 280[/tex]
The pollution level at 4 o'clock in the afternoon is of 280 parts per million.