#3 seems odd.
After 5 minutes (when the flat tire happens), the distance between them should be 15 km. After all, the distance decreases by a rate of 1 km per minute.

Ole is now going 0 km/min and Sven is still traveling at a rate of 1/4 km/min. Sven has to travel 15 km at that rate. 15 km/ .25 km/min = 60 minutes.

I like the way you reasoned that out; and you’re right, it does take 60 minutes from the time Ole has his flat tire for Sven to reach Ole. However, the question asks for the total time from the point when they leave their houses that it takes Sven to reach Ole. So, if you just add the 5 minutes before Ole has his flat tire you’ve got it! Thanks for the question. I love to see alternate solutions!

Challenge your mathematical problem solving skills with problems similar to those found on math contests such as the AMC 8, AMC 10, MATHCOUNTS, or the middle school math olympiads. I post a problem set each week, and then come back later in the week and post the answers and video solutions.

#3 seems odd.

After 5 minutes (when the flat tire happens), the distance between them should be 15 km. After all, the distance decreases by a rate of 1 km per minute.

Ole is now going 0 km/min and Sven is still traveling at a rate of 1/4 km/min. Sven has to travel 15 km at that rate. 15 km/ .25 km/min = 60 minutes.

I like the way you reasoned that out; and you’re right, it does take 60 minutes from the time Ole has his flat tire for Sven to reach Ole. However, the question asks for the total time from the point when they leave their houses that it takes Sven to reach Ole. So, if you just add the 5 minutes before Ole has his flat tire you’ve got it! Thanks for the question. I love to see alternate solutions!

Ahhhh! I fell into the old “read the question” trap! I answered what “I” wanted the question to ask, not what “the question” is asking……

Good lesson – thanks for the problems.