A group of $50,000$ tax forms has an average gross income of $$37,000,$ with an SD

of about $$20,000.$ Furthermore, $20\%$ of the forms have a gross income over

$$50,000.$ A group of $900$ forms is chosen at random for audit. What is the chance

that between $19\%$ and $21\%$ of the forms chosen for audit have gross income over

$$50,000?($Show the box model and the result of your work.$)$

Answer:

$\%$