The sum of first 8 terms of series is -130208
<em><u>Solution:</u></em>
Given that,
2 - 10 + 50 - 250 , ....
n = 8
Find the common ratio between a term and its previous term

Thus common ratio is same
This is a geometric series
<em><u>The sum of terms of geometric sequence is given as:</u></em>

Where,
r is the common ratio
n is the nth term
is the first term of series
From series,

Therefore,

Thus sum of first 8 terms of series is -130208
For this one it's really simple. Just do 90-(-2). It may look confusing right now, but it's really easy. All you need to know is that a negative and a negative cancel out to form a positive. So it's actually 90+2. 92 is the difference.
Since all the volume of the liquid will be contained by all 30 spheres then,
30 V = 3392.92
where V is the volume of each sphere
Solving for V
V = 113.0973
The formula for the volume of the sphere is:
V = (4/3) π r³
Since diameter, D = 2r
V = (4/3) π (D/2)³
V = (4/3) π (1/8) D³
V = (1/6) π D³
Since V = 113.0937
113.0937 = (1/6) π D³
D = 6
Therefore, the diameter is 6 inches (THE THIRD OPTION)