Station 1Station 2Station 3Station 4Station 5$3.699$3.609$3.729$3.679$3.729In the table above, Melissa recorded the price of one gallon of regular gas...
GMAT Problem-Solving and Data Analysis : (PS_DA) Questions
| Station 1 | Station 2 | Station 3 | Station 4 | Station 5 |
|---|---|---|---|---|
| \(\$3.699\) | \(\$3.609\) | \(\$3.729\) | \(\$3.679\) | \(\$3.729\) |
In the table above, Melissa recorded the price of one gallon of regular gas from five different local gas stations on the same day. What is the median of the gas prices Melissa recorded?
$3.679
$3.689
$3.699
$3.729
1. TRANSLATE the problem information
- Given information:
- 5 gas prices from different stations: \(\$3.699\), \(\$3.609\), \(\$3.729\), \(\$3.679\), \(\$3.729\)
- What we need to find: The median of these gas prices
2. INFER the approach needed
- To find the median, we need the middle value when all data is arranged in order
- Since we have 5 values (odd number), the median will be the 3rd value when arranged from smallest to largest
3. VISUALIZE by organizing the data
- Original order: \(\$3.699\), \(\$3.609\), \(\$3.729\), \(\$3.679\), \(\$3.729\)
- Arranged in ascending order: \(\$3.609\), \(\$3.679\), \(\$3.699\), \(\$3.729\), \(\$3.729\)
4. INFER the middle position
- With 5 values, count to the middle: 1st, 2nd, 3rd, 4th, 5th
- The 3rd position contains \(\$3.699\)
Answer: C. \(\$3.699\)
Why Students Usually Falter on This Problem
Most Common Error Path:
Conceptual confusion about median vs. mean: Students remember that median has something to do with "middle" but confuse it with calculating the average (mean). They add all prices and divide by 5: \(\(\$3.699 + \$3.609 + \$3.729 + \$3.679 + \$3.729\) \div 5 = \$3.689\)
This may lead them to select Choice B (\(\$3.689\))
Second Most Common Error:
Weak VISUALIZE skill: Students understand median concept but don't properly organize the data in ascending order. They might look at the original table order and incorrectly identify \(\$3.679\) or \(\$3.729\) as the "middle" value without sorting first.
This may lead them to select Choice A (\(\$3.679\)) or Choice D (\(\$3.729\))
The Bottom Line:
This problem tests whether students can distinguish between different measures of central tendency (median vs. mean vs. mode) and execute the critical step of organizing data before finding the median. The key insight is that median requires ordered data, not just counting positions in the original arrangement.
$3.679
$3.689
$3.699
$3.729