# Math Question: Geometric Series (homework help!)

• Aug 27th 2012, 01:35 AM
mathunnerd
Math Question: Geometric Series (homework help!)
1) Write an expression for S(subscript n), for the series 1+7+13+...
Hence, find the value of n for which S(subscript n) = 833

2) Write an expression for S(subscript n), for an arithmetic series with u(subscript 1) = -30 and d = 3.5
Hence, find the value of n for which S(subscript n) = 105

3) In january 2012, a new coffee shop sells 500 drinks. In february, they sell 600 drinks, then 700 in march, and so on in an arithmetic progression.How many drinks will they expect to sell in december 2012? Calculate the total number of drinks they expect to sell in 2012

4) A geometric series has a common ratio of 0.4 and a sum to infinity of 250. Find the first term.
5) The sum of the first 5 terms of a geometric series is 3798, and the sum to infinity is 4374. Find the sum of the first 7 terms.
6) For a geometric progression with u(subscript 3) = 24 and u(subscript 6) = 3, find S(subscript infinity)

7) Find the common ratio for the geometric series 1/12 + 1/8 + 3/16...
Hence, find the least value of n such that S(subscript n) > 800

8) In geometric series, the sum of the first 3 terms is 304, and the sum of the first 6 terms is 1330, Find the sum of the first 7 terms
9) In geometric series, the sum of the first 4 terms is 10 times the sum of the first 2 terms. If r > 1, find the common ratio

guys! i need some homework help for my girlfriend! I have no idea on this topic so I need some help from you fellas out here! Please provide the workings too! Much thanks!!
• Aug 27th 2012, 03:55 AM
earboth
Re: Math Question: Geometric Series (homework help!)
Quote:

Originally Posted by mathunnerd
1) Write an expression for S(subscript n), for the series 1+7+13+...
Hence, find the value of n for which S(subscript n) = 833

2) Write an expression for S(subscript n), for an arithmetic series with u(subscript 1) = -30 and d = 3.5
Hence, find the value of n for which S(subscript n) = 105

3) In january 2012, a new coffee shop sells 500 drinks. In february, they sell 600 drinks, then 700 in march, and so on in an arithmetic progression.How many drinks will they expect to sell in december 2012? Calculate the total number of drinks they expect to sell in 2012

4) A geometric series has a common ratio of 0.4 and a sum to infinity of 250. Find the first term.
5) The sum of the first 5 terms of a geometric series is 3798, and the sum to infinity is 4374. Find the sum of the first 7 terms.
6) For a geometric progression with u(subscript 3) = 24 and u(subscript 6) = 3, find S(subscript infinity)

7) Find the common ratio for the geometric series 1/12 + 1/8 + 3/16...
Hence, find the least value of n such that S(subscript n) > 800

8) In geometric series, the sum of the first 3 terms is 304, and the sum of the first 6 terms is 1330, Find the sum of the first 7 terms
9) In geometric series, the sum of the first 4 terms is 10 times the sum of the first 2 terms. If r > 1, find the common ratio

guys! i need some homework help for my girlfriend! I have no idea on this topic so I need some help from you fellas out here! Please provide the workings too! Much thanks!!

You'll find all the necessary information here:

Arithmetic progression: Arithmetic progression - Wikipedia, the free encyclopedia
Arithmetic series: Arithmetic Series -- from Wolfram MathWorld
Geometric progression: Geometric progression - Wikipedia, the free encyclopedia
Geometric series: Geometric series - Wikipedia, the free encyclopedia

If you have some difficulties to do these questions please show your work and indicate where you are stuck.