<p>on the the ACT site i was going through a math practice test and did not quite understand the following math problem:</p>
<p>The sum of an infinite geometric series with first term a and common ration r < 1 is given by (a)/(1-r) The sume of a given infinite geometric series is 200, and the common ratio is 0.15. What is the second term of this series?
choices..
f) 25.5 g) 30 h)169.85 j)170 k)199285
the answer is f) 25.5, could someone explain me why?</p>
<p>and i need some advice for the reading section. Of the 35 minutes given i can only complete 3 of the 4 passages. timing is a problem but i have no clue what to do. skimming the passage does not work for me, since i need time comprehending the passage itself. would gladly appreciate any advice.</p>
<p>since your given sum + ratio then
200 = (a) / (1-.15)
a = 170
since its a infinite series that you can get the sum of, it has to be decreasing (if it was increasing the sum would be infinite!) so a * ratio (170 * .15) = 25.5</p>
<p>For reading this is what i did
I started with the last passage then 3rd then 2nd then 1st (since the fiction one is first an usually the hardest) I answered all the questions that asked specifics like (what is paragraph 3 about?) or (the term blahblah in paragraph 7 means…) these forced me to read parts of the passage to answer the question, so i had a little sense of what the passage was without even reading it beforehand and i just answered a few questions ! then i look over the questions and try to skim for the answers</p>
<p>Sorry English is not my first language , so if you could verify this for me would be great.
It said (a) is the first term therefor I thought the second term should be somewhere near (a)…</p>