math
posted by terra .
A stone is tossed vertically into the air from ground level with an initial velocity of 15 m/s. Its height at time t is h(t)=15t4.9t^2.
Compute the stone's average velocity over the time interval [0.5, 2.5].
It says the answer is .3, but I keep getting something not close to that...

avg velocity = (h(2.5)  h(.5) )/(2.5  .5)
I get exactly .3