The speed of the highest point is 0 m/s,

The wat inlet speed is 20m/s,

Then during this journey (15+ 1= 16m).

The average speed is (0+20)÷2= 10m/s,

So the time for athletes to jump into the water from the highest point is

16÷ 10= 1.6s。

2. The average fall speed of athletes per second is (20-0) ÷1.6 =12.5m/sec.

3. Let the time from the highest point to 6m above the water surface be t, then

〔0+(0+ 12.5t)÷2×t = 15+ 1-6

Find t =1.26s.