The answer is 85 volunteers.
We get that we must look for workers working for more than ten hours.
To do that, we must look at the horizontal axis as that will tell us how many hours workers work. We see that the column second to the left represent workers working between six to ten hours.
And the other columns to the right of that column are the workers who work.
Thus by looking at the vertical axis, we see that the 85 volunteers work more than 10 hours
We get that number by adding up all the workers who work between 11-15hours,16-20hours, and 21-25 hours.
Hope that helps!
