Two boats departed from the pier simultaneously in opposite directions. After 3 hours, the distance

| May 22, 2021 | education

Two boats departed from the pier simultaneously in opposite directions. After 3 hours, the distance between them was 144 km. What is the speed of the first boat if the speed of the second boat is 23 km / h?

Let the speed of the 1st boat be equal to c (km / h). We will solve it in two ways.

1) a) In 3 hours the first boat passed 3 * s (km);

b) The second boat passed in 3 hours 3 (hour) * 23 (km / h) = 69 km.

c) As a result, both boats passed 3 * s + 69 = 144 km.

d) Determine the speed of the first boat: 3 * s = 144 – 69 = 75 km, whence s = 75: 3 = 25 (km / h).

2) a) At 1 o’clock both boats pass (3 + s) km / h.

b) In 3 hours, both boats passed (23 + s) * 3 (km) = 144 km.

c) (23 + s) = 144: 3 = 48 (km / h);

d) s = 48 – 23 = 25 (km / h)

Answer: the speed of the 1st boat is 25 km / h.



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