Question

Ian closely monitored the balance of his checking account.
Ian's checking account balance
Month Amount
August $90
September $99
October $54
November $55
December $75
According to the table, when was the rate of decrease greater?

Answer 1

To determine when the rate of decrease in Ian's checking account balance was greater, we can calculate the month-to-month change in his account balance and then compare the rates of decrease between the relevant months.

1. **August to September**:
Change: \( 99 - 90 = 9 \) (Increase)

2. **September to October**:
Change: \( 54 - 99 = -45 \) (Decrease)

3. **October to November**:
Change: \( 55 - 54 = 1 \) (Increase)

4. **November to December**:
Change: \( 75 - 55 = 20 \) (Increase)

Now, we focus on the significant decreases:

- From **September to October**, the balance decreased from **$99 to $54**, which is a decrease of **$45**.

There is no other month where a decrease occurs from September to October, and the other months either show an increase or a small decrease.

Therefore, the rate of decrease was greater from **September to October**, where the amount lost was **$45**.