Question

8. Rebecca's bank Statement Shows a deduction of $1.50 taken out

of her account each week, How many weeks will it take before the

total deduction is $-15?

Answer 1

10 weeks.

This is a simple problem which we can represent as a series as it happens over time with the same constant value of $1.5 per week.

The first term of the A.P. is 1.5

If the common difference is 1.5, find the term for which the term is 15$

nth term of an AP =

`a \: + (n \: - 1)d`

d = 1.5,

a = 1.5

so if

15 = 1.5 + (n-1)1.5

we have that

15 = 1.5 + 1.5n - 1.5

1.5 - 1.5 = 0

So, 15 = 1.5n

Divide both sides by 1.5 to get the unity value of n

n =

`(15)/(1.5)`

n = 10