A certain car increased its average speed by 4 miles per hour in each successive 5-minute interval after the first interval. If in the first 5-minute interval its average speed was 20 miles per hour, how many miles did the car travel in the third 5-minute interval?	Choose the correct choice from the following.
A) 1.0  B) 1.5  C) 2.0  D) 2.5  E) 3.0
In the third time interval the average speed of the car was 20+4+5= 
<gadget id="calculator">20+4+5</gadget>
<output>29</output>
29 miles per hour;   In 5 minutes (1/12 hour) at that speed car would travel 29*1/12=2.5 miles.   Answer: 2.5.
<result>D</result>
A certain car increased its average speed by 4 miles per hour in each successive 5-minute interval after the first interval. If in the first 5-minute interval its average speed was 20 miles per hour, how many miles did the car travel in the third 5-minute interval?