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805+ Level|   Graphs|   Math Related|         
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aoyanf
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For each of four symptoms, the graph shows the percentage chances that 13 Jun 2025, 23:30
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I think the key issue of this quesiton is that it does not specify each sympton is independent, which some of the comments missed here.
Therefore, we cannot calculate the probability of, for example, someone who have all the four symptons.

The guy who created this question did not indent to make us calculate, but he should want us to use information of "The lines for certain symptoms do not continue past a certain day because the chance that someone will have those symptoms beyond that day is less than 1%".

Then we can reach the answer without any multiple calculations.
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For each of four symptoms, the graph shows the percentage chances that 20 Aug 2025, 23:56
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Thanks KarishmaB

Is it "Two or Fewer" because sore throat can be a part of cough?

KarishmaB

We need higher than 98% probability of something. That is as good as certainty, including certainty.

What am I almost certain about? Am I certain that on Day 2, a person will have at least 1 symptom? No. On Day 2, there is 62% probability of nasal drainage, 49% of sore throat, 38% of cough and 16% of fever. What if all other probabilities lie within the circle of nasal drainage? That is the same 62% people see other symptoms also? Then the probability of a person showing at least one symptom will be 62% only.

But what I am certain about is that at Day 10, a person can show at most 2 symptoms. For the other 2 symptoms, the probability is less than 1%. Even if I assume it to be almost 1% and different set of people show the third and fourth symptoms, still there is a more than 98% probability that a person shows 2 or fewer symptoms on Day 10.

ANSWER: two or fewer symptoms on Day 10

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cheshire
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For each of four symptoms, the graph shows the percentage chances that 26 Aug 2025, 16:12
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It's because after day 10 those are the only two symptoms remaining on the graph. The fact that they usually correspond with each other is outside the scope of the question.
agrasan
Thanks KarishmaB

Is it "Two or Fewer" because sore throat can be a part of cough?


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For each of four symptoms, the graph shows the percentage chances that 24 Sep 2025, 00:30
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I can see why this graph interpretation question might be tricky - you need to connect the probability concept with what the graph is actually showing you. Let me walk you through this step-by-step.

Understanding What We're Looking For

The question asks us to find when the probability is greater than 0.98 (or 98%) that someone with a cold will have a certain number of symptoms. Let's think about what this means: we need to be almost certain about how many symptoms a person has.

Key Insight from the Graph

Notice how the problem tells us something crucial: "lines for certain symptoms do not continue past a certain day because the chance that someone will have those symptoms beyond that day is less than 1%." This is your golden clue!

When a line disappears from the graph, it means that symptom has become extremely rare (less than 1% chance).

Step-by-Step Solution

Step 1: Let's track what happens to each symptom by looking at the graph:
- Fever (squares): disappears around day 6-7
- Sore throat (hollow squares): disappears around day 8-9
- Nasal drainage (circles): continues through day 14
- Cough (dots): continues through day 14

Step 2: Now, check day 10 specifically:
- Nasal drainage: still present (around 22%)
- Cough: still present (around 29%)
- Sore throat: gone (below 1%)
- Fever: gone (below 1%)

Step 3: Here's the key reasoning:
On day 10, since sore throat and fever have probabilities less than 1%, the chance someone has either of these is practically zero. That means the maximum number of symptoms someone can realistically have is 2 (just nasal drainage and/or cough).

The probability of having more than 2 symptoms is less than 2% (since that would require having a symptom with less than 1% chance). Therefore, the probability of having "two or fewer" symptoms is greater than 98% (or 0.98).

Answer: Two or fewer symptoms on day 10

Notice how we didn't need "exactly two" because someone might have just one symptom or even zero symptoms. And "one or fewer" would be too restrictive since having two symptoms is still quite possible.

---

You can check out the step-by-step solution on Neuron by e-GMAT to master the systematic approach for interpreting probability graphs and learn the framework that applies to all similar data interpretation questions. You can also explore other GMAT official questions with detailed solutions on Neuron for structured practice here.
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