Question Details

Study the given pattern carefully and select the number from among the given options that can replace the question mark (?) in it.


111475
151631
9?88

Options

A

13

B

22

C

18

D

25

Show Answer

Correct Answer :

Option A

13

13

Solution :

The correct answer is 13.

Let's study the table carefully:

| Col 1 | Col 2 | Col 3 |
|-------|-------|-------|
| 11 | 14 | 75 |
| 15 | 16 | 31 |
| 9 | ? | 88 |

We need to find the relationship between the three numbers in each row. Let us denote the three numbers in a row as A, B, and C.

Step 1: Test Row 1 (11, 14, 75)

Notice that:

A + B = 11 + 14 = 25

B - A = 14 - 11 = 3

Now multiply: (A + B) × (B - A) = 25 × 3 = 75

This matches C = 75!

Step 2: Verify with Row 2 (15, 16, 31)

A + B = 15 + 16 = 31

B - A = 16 - 15 = 1

(A + B) × (B - A) = 31 × 1 = 31

This matches C = 31! The pattern is confirmed:

Pattern: (A + B) × (B - A) = C

This is actually the algebraic identity:

(A + B)(B - A) = B2 - A2

Step 3: Apply the pattern to Row 3 (9, ?, 88)

Let ? = x. Then:

B2 - A2 = C

x2 - 92 = 88

x2 - 81 = 88

x2 = 88 + 81

x2 = 169

x = √169 = 13

Step 4: Verify

(9 + 13) × (13 - 9) = 22 × 4 = 88

The number that replaces the question mark is 13.

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