I posted a question last night but all that happened was I became even more confused.

The homework question is:

Find the sum of each geometric series.

a) S10 in the series $2500 + $2562.50 + $2626.56 + ...

now i would normally use the formula

tn= ar^n-1 except I do not know what tn equals. To find the ^n I need to know what tn is. Now can some one please help me.