Question

Zane's bank charges him a fee for each day his account balance is less than $100. The arithmetic sequence {95.00, 89.50, 84.00, 78.50} describes Zane's bank balance for 4 days. Which explicit formula describes this arithmetic sequence?

There's 4 options/answers what is correct
1. an=95+(n-1)(5.50)
2. an=78.50+(n-1)(-5.50)
3 an=95+(n-1)(-5.50)
4. an= 5.50+(n-1)(-95)

Answer 1

the answer is : an=95+(n-1)(-5.50)

Answer 2

The correct option is;

3. aₙ = 95 + (n - 1)·(-95)

Explanation:

From the question, we have;

The account balance below which a fee is charged = $100

The balance in Zane's bank account for the four days are;

95.00, 89.50, 84.00, 78.50

Therefore, we have the first term of the series, a = 95.00

The common difference are;

78.50 - 84.00 = -5.5

84.00 - 89.50 = -5.5

89.50 - 95.00 = -5.5

Therefore, the common difference is -5.5

The arithmetic sequence is therefore, aₙ = 95 + (n - 1)(-5.50)