Let me walk through each statement for the list:
-1,
4, x, x2,
11,
5, where x is an integer.
Statement I: Median > 1With
6 numbers, the
median is the average of the
3rd and
4th values when sorted. Test key cases:
- x =
0: sorted list is
-1,
0,
0,
4,
5,
11. Median = (
0 +
4)/
2 =
2- x =
1: sorted list is
-1,
1,
1,
4,
5,
11. Median = (
1 +
4)/
2 =
2.5- x =
-2: sorted list is
-2,
-1,
4,
4,
5,
11. Median = (
4 +
4)/
2 =
4- For large |x|, both x and x2 move to the extremes, so the middle stays anchored around the fixed numbers
4 and
5, giving median =
4.5.
In every case, median >
1.
TRUE.Statement II: If range = 15, then no mode.Key Insight: The trick here is that NO integer x actually produces a range of 15!- If x extends the minimum (x <
-1), and max stays
11:
11 - x =
15 gives x =
-4, but then x2 =
16 becomes the new max, making range =
16 - (
-4) =
20, not
15.
- If x2 extends the max: x2 - (
-1) =
15 gives x2 =
14 — not a perfect square.
- If both x and x2 extend the range: x2 - x =
15 gives no integer solutions (discriminant =
61, not a perfect square).
Since the condition 'range = 15' is NEVER true, the entire if-then statement is automatically (vacuously) true. TRUE.Statement III: Average > 2Average = (
-1 +
4 + x + x2 +
11 +
5) /
6 = (x2 + x +
19) /
6We need x2 + x +
19 >
12, i.e., x2 + x +
7 >
0.
The
discriminant is
1 -
28 =
-27 (negative), and since the x2 coefficient is positive, this expression is ALWAYS positive.
TRUE.All three statements must be true.Answer: E