Question

Chris currently has $300 in his lunch account. He spends $9 per week on school lunches. His mother wants to make sure he has at least $150 in his account. After how many weeks will she deposit money to maintain this balance?

Answer 1

After spending $9 per week on lunches, Chris's mother will need to deposit money after the 16th week to ensure the balance remains above $150, as the balance falls below $150 after approximately 16.67 weeks.

Step-by-step explanation:

Chris starts with $300 in his lunch account and spends $9 per week. To find out after how many weeks Chris's mother will need to deposit money to maintain at least a balance of $150, we need to calculate how much money Chris will have left each week and then determine the week during which the amount will fall below $150.

We can set up the equation 300 - 9x ≥ 150, where x is the number of weeks. Solving for x gives us:

300 - 150 = 9x
150 = 9x
x = 150 / 9
x = 16.67

Since Chris's mother wants to maintain a balance of at least $150 and Chris cannot spend a fraction of a week's worth of lunch money, she will need to deposit money after the 16th week to ensure the account does not fall below the $150 threshold.