- 5 : 3
- 3 : 5
- 5 : 6
- 6 : 5

Option 1 : 5 : 3

**Concept used:**

When they are moving in the same direction, the relative speed between the two bodies is the **difference **of their speeds.

When they are moving in the opposite directions, the relative speed between the two bodies is the **sum** of their speeds.

**Formula used:**

Speed × Time = Distance

**Calculation:**

Let the speed of the two train be x m/sec and y m/sec respectively.

Let the total length of the both train be d m

Condition First,

(x + y) × 120 = D ---(1)

(x – y) × 30 = D ---(2)

From equation (1) and equation (2)

(x + y) × 30 = (x – y) × 120

⇒ x + y = 4x – 4y

⇒ 3x = 5y

⇒ x : y = 5 : 3

**So, the ratio of speed of two train is 5 : 3.**

India’s **#1 Learning** Platform

Start Complete Exam Preparation

Daily Live MasterClasses

Practice Question Bank

Mock Tests & Quizzes

Trusted by 2,18,86,739+ Students

Testbook Edu Solutions Pvt. Ltd.

1st & 2nd Floor, Zion Building,

Plot No. 273, Sector 10, Kharghar,

Navi Mumbai - 410210

[email protected]
Plot No. 273, Sector 10, Kharghar,

Navi Mumbai - 410210

Toll Free:1800 833 0800

Office Hours: 10 AM to 7 PM (all 7 days)