Find out co-efficient of variation, if $N = 14$, $\Sigma fx = 280$ and $\sigma$ (S.D.) $= 3$.
(A) 20
(B) 15
(C) 4.67
(D) Zero

Question

Accepted Answer

> [!TLDR]
> Mean $=280/14=20$; C.V. $=(\sigma/\bar x)	imes100=(3/20)	imes100=\mathbf{15}$.

### Step 1 — Find the mean
$$\bar x = \dfrac{\Sigma fx}{N} = \dfrac{280}{14} = 20.$$

### Step 2 — Apply the coefficient-of-variation formula
$$	ext{C.V.} = \dfrac{\sigma}{\bar x}	imes 100 = \dfrac{3}{20}	imes 100 = 15.$$

### Step 3 — Check the traps
- (C) 4.67 comes from wrongly dividing $\Sigma fx$-type numbers or mixing up terms.
- (A) 20 is just the mean, not the C.V.
- (D) Zero would need $\sigma = 0$ (no variation), which is false here. …

Coefficient of Variation

Coefficient of Variation

Step 1 — Find the mean

Step 2 — Apply the coefficient-of-variation formula

Step 3 — Check the traps

Step 1 — Find the mean

Step 2 — Apply the coefficient-of-variation formula

Step 3 — Check the traps

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