Correct Answer - Option 1 : 9 km

**Given:**

When speed is 30 kmph reaches on time

When speed is 18kmph reaches 12 min early

**Formula:**

Time = distance/speed

**Calculation:**

Let the distance be 'x' km

Therefore time taken to cover 'x' km at 30 kmph = x/30 hr

Time taken to cover 'x 'km at 18 kmph = x/18 hr

But it is given that the difference between two timings

⇒ 0 + 12 = 12 min = 12/60 hr = 1/5

⇒ x/18 – x/30 = 1/5

⇒ (30x − 18x)/(18 × 30) = 1/5

⇒ 12x/(18 × 30) = 1/5

⇒ x = (1 × 18 × 30)/(12 × 5)

⇒x = 9 km

**∴** **Length of journey is 9km.**