Question

Evaluate S5 for 300 + 150 + 75 + … and select the correct answer below.

Answer 1

581.25

Explanation:

Use the formula for when the last term is unknown. It is
`s_(n) = (a_(1) - a_(1) (r)^(n) )/(1-r)`.

For this equation
`s_(n)` (sum of the numbers)=
`s_(5)`,
`a_(1)` (amount of first term) = 300, r (ratio)= .5, and n (number of terms) = 5. Knowing this, we plug them into the equation. It would look like:
`s_(10) = (300 - (300)(0.5)^(5) )/(1-0.5)`.

First, we solve the exponents. 0.5 to the fifth power = .03125. Now multiply it by the nearest number in parentheses, which is 300. You should get 9.375.

Now, subtract that from 300. 300 - 9.375 = 290.625. Your numerator is 290.625.

Simplify your denominator. 1 - 0.5 = 0.5.

Divide.

`(290.625)/(0.5) = 581.25`

581.25

I tried to make sure there were no typos! Please let me know if I missed something :)