This question was previously asked in

DSSSB PGT Computer Science Female General Section - 11 July 2021 Shift 1

- 30
- 7.5
- 22.5
- 15

Option 4 : 15

**Given:**

K percent of k percent of 4000 = 90

**Formula used**:

K percent = (K/100)

**Calculations:**

According to the question:

K percent of K percent of 4000 = 90

(K/100) × (K/100) × (4000) = 90

⇒ (K^{2}/10000) × (4000) = 90

⇒ (K^{2} × 4)/10 = 90

⇒ K^{2} = (90 × 10)/4

⇒ K^{2} = 225

⇒ K = √(225)

⇒ K = 15

**Hence, correct option is : (4)**

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