Answer:
The diver descends:
50 seconds x 5 feet/second = 250 feet
The diver ascends:
54 seconds x 4.4 feet/second = 237.6 feet
Therefore, the total change in elevation is:
250 feet (descent) - 237.6 feet (ascent) = 12.4 feet
So, the diver's final elevation is:
0 feet (starting elevation) - 12.4 feet (change in elevation) = -12.4 feet
Therefore, the diver ends up 12.4 feet below sea level.