Answer: Choice B) 388
Note: this is my best guess (see below for what I mean)
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Explanation:
Unfortunately we will have to make a few educated guesses as to the heights of some of the histogram bars. This is due to how the y axis scale is set up. There is too much of a gap when the y increment is 20 units.
The first bar appears to be 20 units high. The second bar is about 30 units high (midpoint of 20 and 40). The third ba is slightly above 40 but not the midway point, so I'd say maybe 42 or so. The fourth bar is 60 units high (more or less). The fifth bar is at about the halfway point of 60 and 80, so it looks like it's 70 units high. The sixth bar is slightly lower than 60 so I'd say 58 is its height. Continue this process and you'll see the list of values shown in the attached image below. Each height is listed directly above the bar it corresponds to.
The heights are then added up: 20+30+42+60+70+58+45+38+19+7 = 389
Since each bar is 1 unit wide, this means that each bar has an area of 1*height = height. In other words, the height of the bar is the same as the area of the bar. If we add up all the heights, we effectively add up all the areas. So the estimated area under this histogram is roughly 389 square units. Keep in mind that I used educated guesses to determine the heights of the bars, so it's likely not to be a perfect method. However, the value 389 is very close to 388 which is choice B. So that's why I'm thinking the final answer is choice B.
Note: if you can, ask your teacher for clarification on how tall each bar is using numeric values (instead of a visual indicator like the histogram).
