25.Brian plans to complete a 100-mile bike race for charity. According to his registration
materials, he will need to ride at an average speed of 12.5 miles per hour if he wants to
complete the course before it closes. On a practice ride the week before the race, Brian
rides 60 miles and tracks his speed. For the first 30 miles, his average speed is 16 miles
per hour, and for the next 30 miles, his average speed is 15 miles per hour. If Brian can
match these speeds for the first 60 miles of the charity race, then he rests for a total of 1
hour after that, what approximate speed must he maintain for the last 40 miles in order
to complete the ride on time?
A) 8 miles per hour
B) 10 miles per hour
C) 13 miles per hour
D) 14 miles per hourHere’s How to Crack It
Draw a Rate Pie, filling in the numbers for the entire ride. You can put in 100 in for the total miles and
12.5 in for the rate. Dividing 100 by 12.5 tells you that Brian has 8 hours to complete the ride. Your pie
will look like this:
Now draw two more pies to determine how much time he would use for the first 60 miles. He rides at 16
miles an hour for the first 30 miles and 15 miles per hour for miles 31–60. Again, divide the number of
miles by the rate to get the time for each portion, which is 1.875 hours for the first part and 2 hours for the
second part.