The graph above shows the height of the tide, in feet, above or below

Difference between height of highest and lowest tide = 2.2 -(-.5) = 2.7 feet
Answer E
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Highest = 2.2

Lowest = -0.5

Difference = 2.2 - (-0.5) = 2.7

Answer: option E



Answer: Option E

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Difference = 2.2 + 0.5 = 2.7

Ans E

2.2 - (-.5) = 2.7
Ans E

Find the distance between the highest and the lowest points as follows:
2.2 - (-0.5) = 2.2 + 0.5 = 2.7

thanks deabas for making clear the logic of the doubt

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

Bunuel Could you please explain the logic? How can height be negative? Why is A incorrect?

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.
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The problem is asking to solve for the range.

From the above graph, we can infer that 2.2 ft is the highest value and (-0.5) is the lowest.

Range= Max- Min
= 2.2- (-0.5)
= 2.7

The correct answer is option E

Hope I wont come across to such question in real GMAT

Have a good day

We are given a graph in which the y-axis displays the height of the tide. We must determine the difference between the heights of the highest and lowest tides.

highest tide = 2.2 feet

lowest tide = -0.5 feet

Thus, the difference between the heights is 2.2 – (-0.5) = 2.2 + 0.5 = 2.7 feet.

Answer: E
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[1] Determine High and Low Points

High: 2.2 ft
Low: -0.5 ft

[2] Calculate Difference

**Trap: make sure to calculate the difference between 2.2 and (NEGATIVE) -0.5, not 0.5.

2.2 - (-0.5)

2.2 + 0.5

= 2.7 (Answer E)

Highest = 2.2
Lowest = -0.5
Difference (Highest - lowest) = 2.2 - (-0.5) = 2.7

Ans: E

Highest=2.2
Lowest=-.5
Difference =2.2-(-.5)=2.7

Answer is E

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This still doesn't make sense to me - the negative/positive in this case just refers to a direction. Negative means it's below a designated baseline, positive means it's above the designated baseline.

So the height of the lowest tide is still 0.5 ft. It's 0.5 ft, and the negative just tells you what direction. So why would you keep the negative in the equation? I'd also think of this as 2.2 - 0.5 = 1.7

Video solution from Quant Reasoning:

Bumping this as I have the exact doubt. Please help!
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This part is actually confusing , but I think it would be helpful to find the difference directly from the diagram. Meaning - Forget signs , Imagine taking a scale and measuring the length between the highest and the lowest tide - it will show 2.7 ft and not 1.7 ft.

Hope this helps !