00:01
So in this problem, it really helps to just reason from the graph and use the grid lines provided in the textbook.
00:06
So we have four questions to figure out.
00:09
And to help us solve the first, i just identify two points that appear to be on the graph.
00:14
When we're at day number 61, that's approximately here, let's say.
00:19
So i estimated from the graph that at day 61, the temperature is approximately 48 degrees fahrenheit.
00:26
And then i found another point that would be roughly on that tangent line as well.
00:30
Which would be at day 91, the temperature appears to be about 61.
00:34
And now we're ready to find the rate of change.
00:37
61 minus 48 over 91 minus 61.
00:42
That would be 13 over 30.
00:45
And 13 divided by 30 is approximately 0 .43.
00:50
So i'm going to say 0 .43 degrees fahrenheit per day is roughly that instantaneous rate of change.
00:57
We're asked to do the same on a later day, which is 191...