The castle is fenced by a wall, the length of which is 4 km 845 m. Sentries are on duty near the wall

The castle is fenced by a wall, the length of which is 4 km 845 m. Sentries are on duty near the wall, who leave the gate and begin to move simultaneously in opposite directions. The speed of one sentry is 3.2 km /, and the second one is twenty-seven fortieth km / h. more. after what time will the sentries meet?

Find the speed of the second sentry.

To do this, add the difference to the speed of the first one.

3.2 + 1 27/40 = 3 2/10 + 67/40 = 32/10 + 67/40 = 128/40 + 67/40 = 195/40 = 4 35/40 = 4 7/8 km / h …

Determine the speed with which the sentries moved towards each other.

To do this, we summarize their speeds.

We get:

3 2/10 + 4 7/8 = 32/10 + 39/8 = 128/40 + 195/40 = 323/40 = 8 3/40 = 8.075 km / h.

We find the time of the meeting.

We divide the length of the wall by the speed of convergence.

4 km 845 m = 4.845.

4.845 / 8.075 = 0.6 hours.

0.6 h = 0.6 * 60 = 36 minutes.

Answer:

The sentries will meet in 36 minutes.