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For each of the last six years, the table shows the price, in Bangladeshi taka, of one unit for each of 4 types of items–Items A through D. The price index shown in the table is the sum of the prices of certain numbers of units of each type of item. For instance, the price index for each year includes the cost of 20 units of Item A.
| Year | A | B | C | D | Price Index |
|---|---|---|---|---|---|
| 1 | 3 | 10 | 9 | 3 | 345 |
| 2 | 3 | 12 | 10 | 1 | 347 |
| 3 | 5 | 12 | 8 | 5 | 407 |
| 4 | 8 | 10 | 6 | 5 | 415 |
| 5 | 8 | 10 | 7 | 4 | 420 |
| 6 | 6 | 8 | 5 | 6 | 358 |
For each of the following statements, select Yes if the statement is true based on the information provided, or No if the statement is false or cannot be determined from the information provided.
The years in which the Item B prices were highest were also the years for which the price index was least.
The prices of Item A were positively correlated with the price index.
The prices of Item C and the prices of Item D were positively correlated.
Let's start by understanding what we're working with. This table shows prices for four items (A, B, C, D) and a price index across 6 years.
Key insights from our initial scan:
Rather than trying to memorize all the numbers, let's focus on understanding relationships and patterns. This approach will help us evaluate the statements much more efficiently.
Original: "The years in which the Item B prices were highest were also the years for which the price index was least."
What we're looking for:
In other words: Do the years with maximum Item B prices perfectly match the years with minimum price index values?
Let's tackle this using a sorting approach. Instead of manually checking each year's values, we can sort the data to immediately identify the patterns we need.
Step 1: Sort by Item B prices (highest to lowest)
SORT by Item B (descending):
→ Years 2 and 3 both have value 12 (highest)
We can immediately see that Years 2 and 3 have the highest Item B prices (both at 12).
Step 2: Sort by Price Index (lowest to highest)
SORT by Price Index (ascending):
→ Years 1, 2, 6 have lowest values (345, 347, 358)
The years with the lowest price indices are Years 1, 2, and 6.
Step 3: Check for matches
Looking at our two sets:
Only Year 2 appears in both sets. For the statement to be true, both Years 2 and 3 would need to appear in the lowest price index set, and Years 1 and 6 should not be in that set.
Statement 1 is FALSE
Teaching Note: Notice how sorting immediately revealed the answer patterns without requiring us to write down every single value. This approach dramatically reduces the chance of calculation errors while giving us a clearer picture of the data relationships.
Original: "The prices of Item A were positively correlated with the price index."
What we're looking for:
In other words: As Item A prices go up, does the price index also tend to go up?
Instead of performing a complex correlation calculation, we can use visual pattern recognition after sorting.
Step 1: Sort by Item A prices (ascending)
SORT by Item A (ascending):
| Year | Item A | Price Index |
|---|---|---|
| 1 | 3 | 345 |
| 2 | 3 | 347 |
| 3 | 5 | 407 |
| 6 | 6 | 358 |
| 4 | 8 | 415 |
| 5 | 8 | 420 |
Step 2: Analyze the pattern in the Price Index column
When we look at the sorted data, we can see a general upward trend in the Price Index as Item A increases:
Despite the slight anomaly with Year 6, the overall pattern shows a clear positive relationship. When Item A increases from 3 to 8, the Price Index generally increases from the 340s to the 410-420 range.
Statement 2 is TRUE
Teaching Note: We've avoided a time-consuming correlation calculation by using visual pattern recognition. On the GMAT, you rarely need to calculate exact correlation coefficients - recognizing the general pattern after sorting is usually sufficient and much faster.
Original: "The prices of Item C and the prices of Item D were positively correlated."
What we're looking for:
In other words: As Item C prices go up, do Item D prices also tend to go up?
Again, let's use sorting and visual pattern recognition to quickly evaluate this statement.
Step 1: Sort by Item C prices (ascending)
SORT by Item C (ascending):
| Item C | Item D |
|---|---|
| 5 | 6 |
| 6 | 5 |
| 7 | 4 |
| 8 | 5 |
| 9 | 3 |
| 10 | 1 |
Step 2: Analyze the pattern in the Item D column
Looking at the sorted data, we can observe that as Item C increases from 5 to 10, Item D generally decreases from 6 to 1. The pattern is quite clear:
This shows a negative correlation, not a positive one. When one variable increases, the other tends to decrease.
Statement 3 is FALSE
Teaching Note: Sorting the data instantly revealed the relationship between these two variables. We didn't need to calculate any correlation coefficients - the visual pattern was sufficient to determine that the correlation is negative, not positive.
Evaluating all three statements:
Our answer is: No, Yes, No
Remember, on table analysis questions, your ability to reorganize data through sorting will often be more valuable than complex calculations. The approach we used here can be applied to virtually any GMAT table question to save significant time while improving accuracy.
The years in which the Item B prices were highest were also the years for which the price index was least.
The prices of Item A were positively correlated with the price index.
The prices of Item C and the prices of Item D were positively correlated.