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Which of the following statement is correct? I. Speed of boat in still water is 8 km/hr. If its speed in downstream is 12 km/hr, then its upstream speed is 10 km/hr. II. A starts from point P at 8 am with speed of 50 km/hr. B starts from point P at 10 am with speed of 75 km/hr towards A. B will catch A at 2 pm. 

Which of the following statement is correct? I. Speed of boat in still water is 8 km/hr. If its speed in downstream is 12 km/hr, then its upstream speed is 10 km/hr. II. A starts from point P at 8 am with speed of 50 km/hr. B starts from point P at 10 am with speed of 75 km/hr towards A. B will catch A at 2 pm.  Correct Answer Only II

Given:

The downstream speed = 12 km/h

The upstream speed = 10 km/h

The speed of A = 50 km/h

The speed of B = 75 km/hr

Concept:

Speed = Distance/Time

Speed of the boat = (Downstream speed + Upstream speed)/2

Calculation:

For statement l

⇒ The speed of boat = (12 + 8)/2 = 20/2 = 10 km/h

⇒ Hence, statement l is wrong

For statement ll

⇒ The distance between A and B at 10 am = 50 × 2 = 100 km

⇒ The time taken by B to catch A = 100/(75 - 50) = 100/25 = 4 hours

⇒ From 10 am 4 hours will be = 2 pm

⇒ Hence, statement ll is correct

∴ The required result will be "Only ll".

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