The couple decide one day that they will definitely go to the beach the next evening if it is sunny...
GMAT Data Sufficiency : (DS) Questions
The couple decide one day that they will definitely go to the beach the next evening if it is sunny without rain at the time they plan to go—and that they will definitely not go if such is not the case. The next morning, the hour-by-hour weather forecast says that in the evening, it will be sunny without rain. Will the couple go to the beach that evening?
- It is raining on the morning and in the afternoon of the day of their planned beach outing.
- The couple always believe that the weather forecast is likely to be accurate.
Understanding the Question
Let's carefully understand what we need to determine. The couple has set a simple rule: they will definitely go to the beach if it's sunny without rain at the time they plan to go, and they will definitely NOT go otherwise.
The morning weather forecast predicts sunny weather without rain for the evening. But here's the key question: Will the couple actually go to the beach that evening?
For this yes/no question to be sufficient, we need to determine with certainty whether they'll go - not "maybe" or "it depends."
Key Insight
The couple's decision depends on what they believe the weather will be like, not necessarily what it actually turns out to be. This distinction is crucial for solving this problem correctly.
Analyzing Statement 1
Statement 1 tells us: It's raining in the morning and afternoon of the day they planned to go.
This might seem relevant, but let's think about what it doesn't tell us:
- What will the actual weather be in the evening?
- More importantly, what do the couple believe about the evening weather?
Just because it's raining earlier doesn't definitively tell us about the evening weather. Weather can change - it could clear up as the forecast suggests, or it could continue raining despite the forecast.
Most critically, we don't know whether the couple still believes the forecast (sunny evening) or if they've changed their minds based on the current rain. Without knowing what the couple believes will happen, we cannot determine if they'll go to the beach.
Statement 1 is NOT sufficient.
[STOP - Not Sufficient!] This eliminates choices A and D.
Analyzing Statement 2
Now let's forget Statement 1 completely and analyze Statement 2 independently.
Statement 2 tells us: The couple always believe that the weather forecast is likely to be accurate.
This is the key to unlocking the answer. Let's connect the logical chain:
- The forecast says it will be sunny without rain in the evening
- The couple always believe the forecast is likely to be accurate
- Therefore, the couple believes it will likely be sunny without rain in the evening
- Since they have a rule to definitely go if it's sunny without rain, and they believe this will be the case...
The couple WILL go to the beach!
Notice that it doesn't matter what the actual weather turns out to be. Their decision is based on their belief, and Statement 2 tells us they believe the forecast.
Statement 2 is sufficient.
[STOP - Sufficient!] This eliminates choices C and E, leaving only B.
The Answer: B
Since Statement 2 alone gives us a definitive "yes" answer while Statement 1 alone does not, the answer is B.
Answer Choice B: "Statement 2 alone is sufficient, but Statement 1 alone is not sufficient."