Question

You jog for 20 minutes a day, after every week you to add 10 minutes. How many weeks will it take for you to be jogging 1 hour and 30 minutes?

Solve with an arithmetic or geometric seuence

Answer 1

Eight weeks

Explanation:

Let's write the first few terms of your sequence.

20, 30, 40, 50, …

This is an arithmetic sequence, because there is a constant difference between consecutive terms.

The formula for an arithmetic sequence is

aₙ = a₁ + d(n -1 )

a₁ is the first term, and d is the difference in value between consecutive terms. Thus,

aₙ = 20 + 10(n-1)

You want to find the value of n when aₙ = 90 min.

90 = 20 + 10(n-1)

70 = 10(n-1)

7 = n - 1

n = 8

It will take you eight weeks until you are jogging for 90 min.