A boat takes 10 hours to go 44 km downstream and 30 km upstream. Again, the same boat takes 13 hours to go 55 km downstream and 40 km upstream. The speed of the boat and the current will be :
speed of boat = 3 kmph, speed of current = 2 kmph
speed of boat = 6 kmph, speed of current = 4 kmph
speed of boat = 9 kmph, speed of current = 2 kmph
speed of boat = 8 kmph, speed of current = 3 kmph

Question

A boat takes 10 hours to go 44 km downstream and 30 km upstream. Again, the same boat takes 13 hours to go 55 km downstream and 40 km upstream. The speed of the boat and the current will be :
speed of boat = 3 kmph, speed of current = 2 kmph
speed of boat = 6 kmph, speed of current = 4 kmph
speed of boat = 9 kmph, speed of current = 2 kmph
speed of boat = 8 kmph, speed of current = 3 kmph

KnowledgeBoat · Accepted Answer

Let x be the speed of the boat in still water and y be the speed of current, Downstream speed = (x + y) km/hr Upstream speed = (x - y) km/hr Time = Given, It takes 10 hours to go 44 km downstream and 30 km upstream. ⇒ .........(1) Given, It takes 13 hours to go 55 km downstream and 40 km upstream. ⇒ ........(2) Substituting , in equation (1), ⇒ 44u + 30v = 10 ....(3) Substituting , in equation (2), ⇒ 55u + 40v = 13 ....(4) Multiply equation (3) by 4, we get : ⇒ 4(44u + 30v = 10) ⇒ 176u + 120v = 40 ....(5) Multiply equation (4) by 3, we get : ⇒ 3(55u + 40v = 13) ⇒ 165u + 120v = 39 ....(6) Subtracting equation (5) from equation (6), we get : ⇒ (165u + 120v) - (176u + 120v) = 39 - 40 ⇒ (165u + 120v - 176u - 120v) = -1 ⇒ -11u = -1 ⇒ u = . Substituting value of u in equation (3), we get : ⇒ 44u + 30v = 10 ⇒ + 30v = 10 ⇒ 4 + 30v = 10 ⇒ 30v = 10 - 4 ⇒ 30v = 6 ⇒ v = . Adding equations (7) and (8) we get, ⇒ x + y + x - y = 11 + 5 ⇒ 2x = 16 ⇒ x = . Substituting value of x in equation (8), ⇒ x - y = 5 ⇒ 8 - y = 5 ⇒ 8 - 5 = y ⇒ y = 3. The speed of the boat in still water is 8 km/hr and the speed of the current is 3 km/hr. Hence, option 4 is the correct option.

Mathematics

Linear Equations

Related Questions

If ∠A = 2x°, ∠B = (6y + 10)°, ∠C = (2x + y)° and ∠D = (x + 10)° are the angles of a quadrilateral, then the values of x and y will be :
x = 40°, y = 20°
x = 20°, y = 40°
x = 45°, y = 15°
x = 15°, y = 45°

Mathematics

Linear Equations

Related Questions

If ∠A = 2x°, ∠B = (6y + 10)°, ∠C = (2x + y)° and ∠D = (x + 10)° are the angles of a quadrilateral, then the values of x and y will be :x = 40°, y = 20°x = 20°, y = 40°x = 45°, y = 15°x = 15°, y = 45°

If ∠A = 2x°, ∠B = (6y + 10)°, ∠C = (2x + y)° and ∠D = (x + 10)° are the angles of a quadrilateral, then the values of x and y will be :
x = 40°, y = 20°
x = 20°, y = 40°
x = 45°, y = 15°
x = 15°, y = 45°