I need help answering #6, 7 and 8

Green Pastures Cheese, LLC Audit Sample Plan for Confirmation of Accounts Receivable 12/31/--	B-9 WL 1/10/--
Objective: Establish the existence and gross valuation of accounts receivable and occurrence of sales by confirmation.
Population: The trial balance of accounts receivable at 12/31/--, with a total book value of $ 269,000
Definition of Misstatement: Any amount that is determined not to be a valid account receivable.
Sampling Technique: Probability-proportionate-to-size
Sampling Parameters:
Tolerable Misstatement:
Total materiality as indicated in the audit plan	$8,000
Less: Estimate of undetected misstatements (50% of overall materiality)	$4,000
Tolerable misstatement for this test	$4,000
Acceptable Level of Risk of Incorrect Acceptance	4.6%
Acceptable Level of Risk of Incorrect Rejection	1.0%
Population Size (Total number of sampling units	250
Estimated Standard Deviation	11.25
Determine the Incorrect Acceptance Coefficient
Determine the Incorrect Rejection Coefficient
Determine the Sample Size (rounded to the next highest round number) SHOW YOUR WORK