#### Answer

a. 115
b. 64
c. Between minutes 9 and 10
d. At 9 minutes

#### Work Step by Step

a. The highest value is the highest point in the graph. It occurs after exactly 10 minutes. The estimated value is around 115.
b. The minimum value is the lowest point in the graph. It occurs after exactly 8 minutes. The estimated value is around 64.
c. The greatest rate of increase is during the period where the graph has the biggest slope heading upwards. It occurs between minutes 9 and 10, where the heart rate goes from around 75 to around 115.
d. Looking at the graph, there is only one place where the line rises to 75 and up, never falling that low again. It looks like the heart rate is at 75 at around 9 minutes.