a. 15
b. 16
c. 17
d. 18
For number 3 to 5: Given an arithmetic sequence with $a_5 = 6$ and $a_{11} = 48$,
3. What is the common difference of this sequence?
a. 5
b. 7
c. 9
d. 11
4. What is the first term of this sequence?
a. -56
b. -34
c. -29
d. -22
5. If we insert five arithmetic means between $a_5$ and $a_{11}$, what are those numbers?
a. 11, 16, 21, 26, 31
c. 12, 18, 24, 30, 36
b. 13, 20, 27, 34, 41
d. 15, 20, 25, 30, 35