Number of bricks needed to make each step, if the stair case has total 30 steps.

Question

In the following situation, does the list of numbers involved in the form a G.P.?

Number of bricks needed to make each step, if the stair case has total 30 steps. Bottom step needs 100 bricks and each successive step needs 2 bricks less than the previous step.

Answer 1

Given: Bricks needed for the bottom step = 100. Each successive step needs 2 bricks less than the previous step. 

∴ Second step from the bottom needs = 100 – 2 = 98 bricks. 

Third step from the bottom needs = 98 – 2 = 96 bricks. 

Fourth step from the bottom needs = 96 – 2 = 94 bricks.

Here the numbers are 100, 98, 96, 94, …. 

Clearly this is an A.P. but not G.P.