Correct Answer - Option 3 : 4.5

**Given:**

d(A) = 6 km

t(B) = 6 hr

D = 42 km

**Formula used:**

S = d/t

**Calculation:**

Let speed of the second man be x kmph

⇒ Distance covered by first person in 4 hours = 6 × 4

⇒ Distance covered by first person = 24 km

⇒ Distance travelled by second person in 4 hours = 4x km

⇒ Total distance travelled by both of them together in 4 hours = 42 km

⇒ 24 + 4x = 42

⇒ 4x = 18

⇒ x = 4.5 km/h

**∴ the speed of the other person is 4.5 km/h.**