Question: What is the next number in these sequences:
a) 5, 11, 17, 23, 29, 35,
b) 89, 85, 81, 77, 73, 69,
c) 4, 15, 26, 37, 48, 59,
d) 1, 2, 4, 8, 16, 32, 64,
e) 15 625, 3 125, 625, 125, 25,
f) 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89,
This last one is called the Fibonacci Sequence - feel free to google the answer
1. **Problem Statement:** Find the next number in each of the given sequences.
2. **Sequence a:** $5, 11, 17, 23, 29, 35$
- This is an arithmetic sequence increasing by $6$ each time.
- Formula: $a_{n+1} = a_n + 6$
- Next number: $35 + 6 = 41$
3. **Sequence b:** $89, 85, 81, 77, 73, 69$
- This is an arithmetic sequence decreasing by $4$ each time.
- Formula: $a_{n+1} = a_n - 4$
- Next number: $69 - 4 = 65$
4. **Sequence c:** $4, 15, 26, 37, 48, 59$
- This is an arithmetic sequence increasing by $11$ each time.
- Formula: $a_{n+1} = a_n + 11$
- Next number: $59 + 11 = 70$
5. **Sequence d:** $1, 2, 4, 8, 16, 32, 64$
- This is a geometric sequence doubling each time.
- Formula: $a_{n+1} = 2 \times a_n$
- Next number: $64 \times 2 = 128$
6. **Sequence e:** $15625, 3125, 625, 125, 25$
- This is a geometric sequence dividing by $5$ each time.
- Formula: $a_{n+1} = \frac{a_n}{5}$
- Next number: $\frac{25}{5} = 5$
7. **Sequence f (Fibonacci Sequence):** $1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89$
- Each number is the sum of the two preceding numbers.
- Formula: $a_{n} = a_{n-1} + a_{n-2}$
- Next number: $55 + 89 = 144$
**Final answers:**
a) $41$
b) $65$
c) $70$
d) $128$
e) $5$
f) $144$