oludayo
GMATinsight
Bunuel
The graph above shows the height of the tide, in feet,
above or below a baseline. Which of the following is closest to the difference, in feet, between the heights of the highest and lowest tides on July 13 at Bay Cove?
(A) 1.7
(B) 1.9
(C) 2.2
(D) 2.5
(E) 2.7
Highest = 2.2
Lowest = -0.5
Difference = 2.2 - (-0.5) = 2.7
Answer: option E
Hi, im a little confused here. I do get the logic behind how we got E however the question here says 'height of tidal waves' right? so in reality can the height be negative? I would have figured, get the absolute numbers and find the difference between the highest and lowest absolute number. Kindly correct me where I am wrong. Thanks
oludayo and
NerdyEmoOne - see the text in bold. Easy to miss. There is a baseline. ". . .
above or below a baseline . . ." implies "above or below a baseline [height]."
Height isn't negative. It's lower than the baseline, but it isn't negative as in "negative height." We don't know the "baseline" tidal height, but we know there is one, and prompt doesn't say it equals zero.
Neither could it, really; if you think about tides and where they break, and roll in or out, it varies, but there is always water on the coastline (save when tsunamis hit).
So the baseline likely is some line that runs parallel to the beach where, say, if you were to walk to that point and into the water, between high and low tide, your feet and lower legs would be in X feet or inches of water.
When the tide comes in, that's the high point. The water might be up to your waist. When the tide goes out the most, maybe just your feet would be covered.
The deviation from the baseline is measured over time. That's clear from the x-axis. But baseline is also determined by some normal or average or regular height of the tide. And the implication is that the baseline (tide height) is positive.
Hope that helps.