Question 22. An ant is walking along the sides of an equilateral triangle. The speed at which it travels along the three sides are 5 centimeters a minute, 15 centimeters a minute, and 20 centimeters a minute, as shown. What is the average speed in centimeters a minute at which the ant walks the whole perimeter of the triangle? Let's start off by drawing our triangle. Now, since we are never given a length of any of the sides, but we know that all the sides are equal, for simplicity, let's say that each of the sides of the triangle are 20 centimeters, since we know that the ant at its fastest speed moves 20 centimeters a minute. This means we can say that it takes it one minute to travel that side of the triangle. Next, we could say it takes it four minutes to walk the next side, and then 1.33 minutes the last side. We can add these three times up and get 6.33 minutes to walk across the whole perimeter of the triangle. And, since we said that it was 20 centimeters, when we multiply that by 3, we get 60 centimeters traveled in 6.33 minutes. Now, to have this fit any of the answers, we multiply this by 3, and we will get 180 divided by 19, or answer C.

ant

equilateral triangle

average speed

perimeter

calculation