My brother set out for an outing at 8: 20 in the morning at a speed of 4 kilometers per hour. At 0: 20 in the morning/kloc-0: 00, my brother chased him from the same place by bike. If my brother wants

My brother set out for an outing at 8: 20 in the morning at a speed of 4 kilometers per hour. At 0: 20 in the morning/kloc-0: 00, my brother chased him from the same place by bike. If my brother wants to join Solution: 1 1: 00-8: 20 = 2 hours and 40 minutes = 8/3 hours.

11:00-10: 20 = 40 minutes = 2/3 hours

Let my brother's speed be x kilometers per hour.

2/3 x≥4×8/3

x≥ 16

So my brother's speed should be at least16 km/h.