Averaging Meters
📚 What You'll Learn
- How to add decimal numbers by lining up decimal points
- Dividing decimals by bringing the decimal straight up
- Working with remainders and rounding to the nearest hundredth
- Finding the average distance of multiple trials
We conducted three trials with our motor racer. The distances were one point zero four meters, point nine eight meters, and one point zero two meters.
Now here's the challenge. What's the racer's average distance?
We already know how to find an average. Remember, from a previous lesson, we found the total of all of the trials by using addition. Then, we split or divided that total by the number of trials.
But this time, our data involves numbers with decimals. That makes the addition and the division a bit more challenging. Let's see how to handle that.
When adding decimals, it's important to remember what we learned before. The decimal point does not float around. It's fixed. That means when we line up the numbers, the decimal points stay stacked in a straight column.
So as you write the numbers, make sure the decimal point is lined up. Add one point zero four, plus point nine eight, plus one point zero two. The total distance is three point zero four meters.
Now, we need to divide or split that total into three equal parts to find the average.
First, look at the whole number part. Three goes into three one time.
Next, bring that decimal point straight up into the answer. It stays fixed.
Now look at the tenths place. We bring down the zero. How many times does three go into zero? Zero times. So I write zero in the tenths place.
Finally, bring down the four in the hundredths place. Three goes into four one time.
At this point, we still have one left over. If we wanted to keep dividing into the thousandths or even ten thousandths, we could add extra zeros after three point zero four. That doesn't change its value, but it lets us keep going with the division.
For our purposes though, rounding to the nearest hundredth of a meter is perfect. So the answer is one point zero one.
Notice how place value helps us again. When adding decimals, we keep the decimal points all lined up. When dividing, the decimal goes straight up into the answer.
That's how we find the average distance of our motor racer.