During a year end an audit, discrepancies were found in a company’s invoice ledger. Consequently, the controller had all invoices in the year checked to determine if they were correctly recorded in the ledger. The proportion of incorrectly recorded invoices was found to be 0.04. The controller instituted a new procedure for processing invoices. Subsequently a random sample of 500 invoices was checked to determine whether the proportion of incorrectly recorded had changed from 0.04. a) Perform a hypothesis test at 5% level if eleven of the sample invoices were recorded incorrectly.
b) What is implied by the test result?​