1/2 * 1/2 = 1/4 there is a 25% chance that they will both occur
It depends really. If you stay close to the present, then predicting future results isn't too bad. The further you go out, the more unpredictable things get. This is because the points may deviate from the line of best fit (aka regression line) as time wears on. Of course, it also depends on what kind of data we're working with. Some pairs of variables are naturally going to correlate very strongly together. An example would be temperature versus ice cream sales.
The last option
I hope this is right let me know if its wrong and ill correct it
A geometric series is written as 
, where 
is the first term of the series and 
is the common ratio.
In other words, to compute the next term in the series you have to multiply the previous one by .
Since we know that the first time is 6 (but we don't know the common ratio), the first terms are
.
Let's use the other information, since the last term is 
, we know that 
, otherwise the terms would be bigger and bigger.
The information about the sum tells us that
We have a formula to compute the sum of the powers of a certain variable, namely
So, the equation becomes
The only integer solution to this expression is 
.
If you want to check the result, we have
and the last term is
35 squared + 35 squared
rad 2450
35 rad 2
