Question

Ft.

2. A slow-moving bug is climbing a 15 ft. pole to reach a critical food source. It manages to climb 3
each day, but at night it slides back down 1 ft. How many days will it take the bug to reach the top and
get the food?

Answer 1

Explanation:

a0 = 0 ft (starting on the ground)

a1 = a0 + 3 - 1 = a0 + 2

an = an-1 + 3 - 1 if an-1 +3 < 15

an = an-1 + 3 if an-1 + 3 >= 15

so, we need to find the n, so that

an = an-1 + 2 >= 12

but by looking at the structure, we see that every step just adds 2 ft to the total height.

an = a0 + 2n = 0 + 2n = 2n

2n >= 12

n >= 6

so, with day 6 the bug reaches 12 ft height. in day 7 it gets up to 15 ft and reached its goal.

it will take 7 days for the bug to reach the top and get the food.