Please help me with these problems

Which equation represents the partial sum of the geometric series?

Look at this pattern ; 1,4,9, number 10000 belongs in this pattern . what’s the place of this number?

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)