Nia wants to check whether the finance charge applied in her credit card statement is correct. To do this, she needs to calculate the average daily balance in her account for the previous billing cycle. The billing cycle is 31 days. What was Nia's average daily balance in this billing cycle?

\begin{tabular}{|c|c|}
\hline
Days & Balance \\
\hline
7 & [tex][tex]$\$[/tex]745.00[tex]$[/tex] \\
\hline
10 & [tex]$[/tex]\[tex]$585.15$[/tex][/tex] \\
\hline
7 & [tex][tex]$\$[/tex]245.20[tex]$[/tex] \\
\hline
7 & [tex]$[/tex]\[tex]$90.75$[/tex][/tex] \\
\hline
\end{tabular}

A. [tex][tex]$\$[/tex]13,420.00[tex]$[/tex]
B. [tex]$[/tex]\[tex]$13,418.00$[/tex][/tex]
C. [tex][tex]$\$[/tex]800.00[tex]$[/tex]
D. [tex]$[/tex]\[tex]$432.84$[/tex][/tex]
E. [tex][tex]$\$[/tex]430.48$[/tex]



Answer :

To determine if the finance charge applied in Nia’s credit card statement is correct, we need to calculate the average daily balance for her billing cycle. Here is a detailed step-by-step solution for this:

1. Understand the Problem:
- We need to calculate the average daily balance for a 31-day billing cycle.
- Nia has balances and corresponding days as follows:
- 7 days with a balance of [tex]$745.00 - 10 days with a balance of $[/tex]585.15
- 7 days with a balance of [tex]$245.20 - 7 days with a balance of $[/tex]90.75

2. Calculate the Total Weighted Balance:
- We multiply each balance by the number of days it was held to get the total weighted balance.
- For the first entry: [tex]\(7 \times 745.00 = 5215.00\)[/tex]
- For the second entry: [tex]\(10 \times 585.15 = 5851.50\)[/tex]
- For the third entry: [tex]\(7 \times 245.20 = 1716.40\)[/tex]
- For the fourth entry: [tex]\(7 \times 90.75 = 635.25\)[/tex]

3. Sum Up the Total Weighted Balances:
- Total weighted balance = [tex]\(5215.00 + 5851.50 + 1716.40 + 635.25 = 13418.15\)[/tex]

4. Calculate the Average Daily Balance:
- To find the average daily balance, we divide the total weighted balance by the number of days in the billing cycle.
- [tex]\( \text{Average Daily Balance} = \frac{13418.15}{31} = 432.84354838709675 \)[/tex]

5. Match the Calculated Average Daily Balance to given options:
- Among the given options, the one that matches our calculated average daily balance (rounded to two decimal places) is:
- D. [tex]$432.84 Therefore, Nia’s average daily balance for the billing cycle is \$[/tex]432.84.