For how many minutes they have run?---**Question Stem:** 40. Two horses run in opposite directions from the same spot. Their running speeds are 30 km/h and 40 km/h respectively. When they are 3500 m apart, for how many minutes have they run? **Other Relevant Text:** 30 km/h = 30000 m/s, 40 km/h = 4000 m/s 3.5 / (30 + 40) = 0.05 They have ran 0.05 minutes.

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We have two horses starting from the same point and running in opposite directions. Horse 1 runs at 30 kilometers per hour, and Horse 2 runs at 40 kilometers per hour. We need to find how long they have been running when they are 3500 meters apart. First, we need to convert the speeds from kilometers per hour to meters per minute. For Horse 1: 30 kilometers per hour equals 30 times 1000 divided by 60, which gives us 500 meters per minute. For Horse 2: 40 kilometers per hour equals 40 times 1000 divided by 60, which gives us 666.67 meters per minute. Since the horses are running in opposite directions, their relative speed is the sum of their individual speeds. We add 500 meters per minute plus 666.67 meters per minute to get a relative speed of 1166.67 meters per minute. This means they are separating at this combined rate.