Most car engines need at least 87 octane to avoid “knocking” or “pinging,” terms used to describe the preignition that can happen when a fuel’s octane is too low. An engineer is designing an experiment to raise the octane of an ethanol-based fuel. From previous studies, she thinks that with 8 experimental runs, she will have a power of 0.90 to detect a real increase of 3 points in the mean octane.

a) If the actual increase is only 1 point, will the power be increased or decreased?

b) If she wants the power to be the same, but she is interested in detecting an increase of only 1 point, what will she need to do?