I am reposting to correct a mistake.
I forgot to add a decimal point.
An object is fired vertically upward with an initial speed of 68.6 meters/second. After t seconds, the height is shown by
y = -4.9 t^2 + 68.6 t meters. Given that this object has an initial speed of 68.6 m/s, what is the maximum height it will reach? How long did it take the rocket to reach the maximum height?
See
http://www.jiskha.com/display.cgi?id=1369047938