Central Tendency & DispersionMTP May 20Question 3164 of 473
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If x\displaystyle x and y\displaystyle y are related by 2x+3y+4=0\displaystyle 2x+3y+4=0 and SD of x\displaystyle x is 9\displaystyle 9, then SD of y\displaystyle y is

Options

A22\displaystyle 22
B6\displaystyle 6
C5\displaystyle 5
D24\displaystyle 24
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Correct Answer

✅ Option b — 6\displaystyle 6

All Options:

  • A22\displaystyle 22
  • B6\displaystyle 6
  • C5\displaystyle 5
  • D24\displaystyle 24

Detailed Solution & Explanation

**Given:** 2x+3y+4=0\displaystyle 2x + 3y + 4 = 0, SD(x)=9\displaystyle SD(x) = 9 **Step 1: Express y\displaystyle y in terms of x\displaystyle x.** 3y=−2x−43y = -2x - 4 y=−23x−43y = -\frac{2}{3}x - \frac{4}{3} **Step 2: Find SD of y\displaystyle y.** For y=a+bx\displaystyle y = a + bx: SD(y)=∣b∣⋅SD(x)\displaystyle SD(y) = |b| \cdot SD(x) Here b=−23\displaystyle b = -\frac{2}{3}: SD(y)=∣−23∣×9=23×9=6SD(y) = \left|-\frac{2}{3}\right| \times 9 = \frac{2}{3} \times 9 = 6 Hence, **Option B** is the correct answer.

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