Algebra 2 Unit 1 Inv. #5 HW
Name: ___________________________ Period: _____
For Exercises 1-2, find the sum of the series.
1. 121 + 128 + 135 + … + 233
2. 83 + 81 + 79 + … -19
For exercises 3-6, do the following.
a) Find the number of terms in the series.
b) Find the sum of the series.
3.
17 + 21 + 25 + … + 89
5. 6 + 6.3 + 6.6 + … + 25.2
4. 223 + 214 + 205 + … + (-56)
6. -10 + (-8.2) + (-6.4) + … + 42.2
7. Auditoriums are often designed so that there are fewer seats per row for rows closer to the stage. Suppose you
are sitting in Row 23 at an auditorium and notice that there are 65 seats in your row. It appears that the row in front of
you has 63 seats and the row behind you has 67 seats. Suppose this pattern continues throughout the auditorium. You
count a total of 42 rows in the auditorium. How many seats does the auditorium contain?
8. A child builds a pyramid out of multiple decks of playing cards. As he starts from the bottom-up, the layers are
numbered starting at the base. Suppose he creates the sixth layer by using 12 cards. His friend notes that the fifth layer
is made out of 16 cards, and the boy is planning to use 8 cards to create the seventh layer. Suppose this pattern
continues throughout the pyramid. The boy who is building says that his pyramid will have a total of eight layers. How
many cards does it take to build the pyramid?
9. A finite series has 73 terms with 𝑎7 = 21.4 and 𝑎13 = 32.8. What’s the sum of the series?
10. A finite series has a sum of 81,674 with a first term of 912 and a final term of -70. How many terms are in the series?