Question

Jacob has $1,000 in a checking account and withdraws $40 each week. His account requires a minimum balance of more than $400. Write an inequality to model the number of weeks, x, that he can withdraw $40 to maintain the minimum balance requirement.

Answer 1

`1000-40x>400`

Explanation:

Let's call B the balance of Jacob's checking account. Each week he withdraws $40 from his actual balance of $1000, so if x is the number of weeks, the account's balance is

B=1000-40x

The balance must be more than $400, which means

`1000-40x>400`

That is the inequality to model the situation. If we wanted to know the limit for x, we can solve the inequality. Operating:

`1000-400>40x`

600>40X

`x<(600)/(40)`

Or x<15

Which means Jacob can withdraw $40 14 times at most to maintain the minimum balance requirement