Answer:
25 seconds
Step-by-step explanation:
Two methods:
1) Calculate Tyana's speed in m/sec: 4m/5sec = 0.8 m/sec. Now find the number of seconds, x, needed to travel 20 meters:
x*(0.8 m/sec) = 20 m
x = 20 m/(0.8 m/sec)
x = 25 seconds
2) Do a proportion. If Tyana can swim 4 meters in 5 sec, then she can do 8 meters in 10 seconds. That also then means 16 meters in 20 seconds. Another 5 seconds adds another 4 meters, for a total of 20 meters in 25 seconds.
