Final answer:
The maximum contribution Zack may make to a defined contribution Keogh plan is $28,827.50.
Step-by-step explanation:
In order to determine the maximum contribution Zack may make to a defined contribution Keogh plan, we need to consider the contribution limits set by the IRS. For 2020, the maximum contribution limit for a defined contribution Keogh plan is the lesser of 25% of the earned income or $57,000.
In this case, Zack's earned income is $115,310. Therefore, the maximum contribution he may make to a defined contribution Keogh plan is the lesser of:
25% of $115,310 = $28,827.50
$57,000
So, the maximum contribution Zack may make to a defined contribution Keogh plan is $28,827.50.