Final answer:
To estimate when Aaron will need to pay for additional data, we calculate the rate of his data usage and compare it to his data plan. If he exceeds his data plan, he will need to pay for additional data.
Step-by-step explanation:
To answer this question, we need to find the number of days in the billing period and calculate how much data Aaron has used up to the 21st day. Then we can determine the rate at which he is using data and estimate when he will need to pay for additional data.
Let's assume the billing period is 31 days. Aaron received a message that he used 80% of 3GB of data, which is 0.8 x 3GB = 2.4GB. So, on the 21st day, he has used 2.4GB.
To find the rate of data usage per day, we can divide the total data used by the number of days. The rate is 2.4GB / 21 days = 0.1143GB or approximately 114.3MB per day.
If Aaron has 3GB of data and he is using 114.3MB per day, he will need to pay for additional data when he exceeds 3GB. So, we can estimate that he will need to pay for additional data when he uses more than 3GB.