Final answer:
The probability that Ben's first hit will be on the eighth pitch is approximately 0.0419.
Step-by-step explanation:
To find the probability that Ben's first hit will be on the eighth pitch, we need to calculate the probability of him not hitting the ball in the first seven pitches and then hitting it on the eighth pitch.
The probability of him not hitting the ball in a single pitch is 1 - 0.20 = 0.80.
Since each pitch is independent, the probability of him not hitting the ball in the first seven pitches is (0.80)^7 = 0.2097152.
Therefore, the probability of his first hit being on the eighth pitch is 0.2097152 * 0.20 = 0.0419430 (rounded to the nearest ten-thousandth).