The mean is not the same thing as median mean=78+81+85+87=331 mean=331/4=82.75 median is the middle number, but you have a par set of numbers, so your median will be the middle numbers 78,81,85,87 , which are 81+85=166, 166/2=83 83 is your median
A boy swimming at an elevation of 3 feet below sea level. This is the answer because the boy is only 3 feet away from sea level while the bird is 10 feet away form sea level.