Question

The number of windows on each floor form an arithmetic sequence; 124 windows on the first floor, 116 windows on the second floor. Derive the explicit formula from the given information and find how many windows are on the tenth floor.

Answer 1

Formula is 132 - 8n, and there are 52 windows on 10th floor.

Explanation:

difference = 116-124 = -8 ( 8 less windows for every floor you go up)

the first fllor has 124 windows

Formula:

`a_(1) = 124`

`a_(n) = 124 + (-8)(n - 1)` = 132 - 8n

10th Floor:

`a_(10) = 124 + (-8)(10 - 1) = 124 + (-8)(9) = 124 - 72 = 52 windows`