I need help in this with explanation ​

Which equation represents the partial sum of the geometric series?

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

The evening newspaper is delivered at a random time between 5: 30 and 6: 30 pm. dinner is at a random time between 6: 00 and 7: 00 pm. each spinner is spun 30 times and the newspaper arrived 19 times before dinner. determine the experimental probability of the newspaper arriving before dinner.