00:01
In this problem, the temperature t of t is given by 70 plus 10 times sine of pi t over 12, where t is the time in hours after 9 a .m.
00:25
In subpart a, we are asked to find out the temperature t at 9 a .m.
00:31
So this corresponds to t.
00:34
Equals to 0 since 0 hours have passed after 9 a .m.
00:39
So now substituting the value of t as 0, we get t of 0 equals to 70 plus 10 times sine of pi times 0 over 12 which is clearly equal to 0 and we know that sign of 0 equals to 0.
01:01
So we get t of 0 to be equal to 70.
01:06
And since the units is degrees fahrenheit, we get 70 degrees fahrenheit as the answer for subpart a.
01:18
Next, moving towards subpart b, in subpart b, we are asked to find the temperature at 3pm.
01:26
So this corresponds to t equals to 6 since 6 hours have passed after 9am.
01:34
So now substituting the value of t as 6, we get t of 6 equals to 70 plus 10 times sine of pi times 6 over 12.
01:48
Here 6 and 12 get cancelled 2 times.
01:53
So therefore we have t of 6 to be equal to 70 plus 10 times sine of pi over 2.
02:04
Since sine of pi over 2 equals to 1 we get 70 plus 10 which is equal to 80 so therefore t of 6 is equal to 80 degrees fahrenheit and this is our final answer for subpart b.
02:22
In subpart c we are asked to find out the average temperature which is denoted by t average average between 9am to 9 p .m.
02:38
So now we know that the value of t corresponding to 9am is 0 and the value of of t corresponding to 9 p m is 0 plus 12 which is 12.
02:51
So let us look at the formula for t average...