Question 37·Easy·One-Variable Data Distributions; Measures of Center and Spread
The table shows the amount of rainfall, in centimeters, recorded in a town over six consecutive days.
| Day | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday |
|---|---|---|---|---|---|---|
| Rainfall (cm) | 0.2 | 0.0 | 0.3 | 0.5 | 0.4 | 0.6 |
What was the mean daily rainfall, in centimeters, for the six-day period? (Round your answer to the nearest hundredth.)
For mean (average) questions from a small data table, add the values quickly—grouping decimals that make whole numbers helps—then divide by the number of data points. Once you have the decimal, pay close attention to the place value the question asks for (here, the hundredth) and use the next digit to round correctly. Finally, compare your rounded result carefully with the answer choices, which may include common rounding mistakes as traps.
Hints
Think about what "mean" means
To find the mean (average) of several numbers, what two main steps do you always take with the data values?
Work with the data in the table
First, add together the six rainfall amounts from Monday through Saturday to find the total rainfall for the six days.
Use the total to find the mean
Once you have the total rainfall, divide that total by 6 (the number of days). Then think about how to round your result to the nearest hundredth.
Check the decimal places
After dividing, look at the third decimal place (the thousandths place) to decide whether to round the second decimal place up or keep it the same.
Desmos Guide
Use Desmos to compute the mean directly
In Desmos, type the expression (0.2 + 0 + 0.3 + 0.5 + 0.4 + 0.6) / 6 and look at the numerical output. Then round that value to the nearest hundredth and match it to one of the answer choices.
Step-by-step Explanation
Recall how to find the mean
The mean (average) of a set of numbers is found by:
- Adding all the numbers together to get the total.
- Dividing the total by how many numbers there are.
Here, there are 6 days of rainfall, so we will divide the total rainfall by .
Add the rainfall amounts
Add the six rainfall values from the table:
Group them to make it easier:
Now add these results:
So the total rainfall over the six days is centimeters.
Divide to find the mean rainfall
Now divide the total rainfall by the number of days (6):
Using division:
This decimal repeats with 3s.
Round to the nearest hundredth and choose the answer
To round to the nearest hundredth (second decimal place):
- Look at the thousandths place (the third decimal digit), which is .
- Since , we keep the hundredths place as it is.
So the mean daily rainfall is centimeters.
Among the choices, this corresponds to B) 0.33.