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Below is an "oracle" function. An oracle function is a function presented interactively. When you type in a $t$ value, and press the --f--$>$ button the value $f(t)$ appears in the right hand window. There are three lines, so you can calculate three different values of the function at one time.

The function f(t) represents the height in feet of a ball thrown into the air, $t$ seconds after it has been thrown. Approximate the velocity 0.47 seconds after the ball has been thrown by computing the average velocity over a short interval containing this time.

Velocity at $0.47 \approx$ You can use a calculator or just let webwork do the arithmetic for you. Your answer must be within 1% of correct answer to be marked "correct".

tf(t)

Remember this technique for finding velocities. Later we will use the same method to find the derivative of functions such as $f(t)$.