A bar graph with one bar per observation gives you a list of counts: each bar’s height is one data value. The mean is the total shared equally, so read every bar height and use a Desmos list to find the average. Don’t confuse the length of each observation with the number of observations.
Hints
- Hint 1
Each bar represents one observation, and its height gives the number of birds seen. Read the heights from left to right; the numbers on the horizontal axis label the observations, not their bird counts.
- Hint 2
The mean uses every bar height. Put the five heights into a Desmos list and find its mean. How many observations are sharing the total?
Step-by-step
Read the bars and find their mean
Step 1Read the five bird counts
The horizontal axis labels the observations, and each bar’s height gives its bird count. Reading left to right gives . The minutes describe how long each observation lasted; they aren’t another count to average.
- Step 2
Enter the counts as a list
Type . Desmos stores these five bar heights as the list , with one entry for each observation.
- Step 3
Find the mean
The mean is the total shared equally among the observations. Type ; Desmos shows . Count each observation once when finding a mean. So the mean is birds per observation. Choice B.