Consider the sets S, T and U, where S = {31, 14, 64, 22, 43, 66}, T = {x, 31,...
GMAT Two Part Analysis : (TPA) Questions
Consider the sets \(\mathrm{S}\), \(\mathrm{T}\) and \(\mathrm{U}\), where \(\mathrm{S = \{31, 14, 64, 22, 43, 66\}}\), \(\mathrm{T = \{x, 31, 14, 64, 22, 43, 66\}}\), and \(\mathrm{U = \{y, 31, 14, 64, 22, 43, 66\}}\). The mean of \(\mathrm{T}\) is 5 less than the mean of \(\mathrm{S}\). The median of \(\mathrm{U}\) is 4 less than the median of \(\mathrm{S}\).
Select the value of x and the value of y consistent with the statements given. Make two selections, one in each column.
Visualization
Let's create a table to track our sets and their properties:
Set | Elements | Mean | Median |
S | {31, 14, 64, 22, 43, 66} | ? | ? |
T | {x, 31, 14, 64, 22, 43, 66} | Mean(S) - 5 | - |
U | {y, 31, 14, 64, 22, 43, 66} | - | Median(S) - 4 |
Calculate S's Properties
First, let's find the mean of S:
- Sum = 31 + 14 + 64 + 22 + 43 + 66 = 240
- Mean of S = \(240 \div 6 = 40\)
For the median, we need to sort S:
- S sorted = {14, 22, 31, 43, 64, 66}
- With 6 elements (even count), median = \((31 + 43) \div 2 = 37\)
Phase 2: Understanding the Question
We need to find:
- Value x such that T has mean = \(40 - 5 = 35\)
- Value y such that U has median = \(37 - 4 = 33\)
Key insight: Both T and U have 7 elements (the 6 from S plus one additional element).
Phase 3: Finding the Answer
Finding x (for set T)
T has 7 elements with sum = 240 + x
- Mean of T = \((240 + x) \div 7 = 35\)
- \(240 + x = 245\)
- \(x = 5\) ✓
Finding y (for set U)
U has 7 elements. When sorted, the median is the 4th element (middle of 7).
We need the 4th element to equal 33.
Let's determine where y must be positioned:
- If y ≤ 14: sorted U = {y, 14, 22, 31, 43, 64, 66} → 4th element = 31 ✗
- If 14 < y ≤ 22: sorted U = {14, y, 22, 31, 43, 64, 66} → 4th element = 31 ✗
- If 22 < y ≤ 31: sorted U = {14, 22, y, 31, 43, 64, 66} → 4th element = 31 ✗
- If 31 < y < 43: sorted U = {14, 22, 31, y, 43, 64, 66} → 4th element = y = 33 ✓
Since we need the 4th element to be 33, and this only happens when y itself is the 4th element, \(y = 33\).
Phase 4: Solution
Our final answers are:
- X = 5
- Y = 33
Both values are in our answer choices and satisfy all the given conditions.