Let's solve this step by step based on the information provided in the image.
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Problem Summary:
Sally grows strawberries:
- Year 1: 6 seeds
- Year 2: 18 seeds
- Year 3: 54 seeds
We are given a table:
| X (Year) | 1 | 2 | 3 |
|----------|---|---|---|
| Y (Seeds)| 6 | 18| 54|
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Part A: Is this arithmetic or geometric?
#### Step 1: Check if it’s arithmetic
In an
arithmetic sequence, the difference between consecutive terms is constant.
Check the differences:
- 18 - 6 = 12
- 54 - 18 = 36
The differences are
not constant (12 ≠ 36), so it's
not arithmetic.
#### Step 2: Check if it’s geometric
In a
geometric sequence, the ratio between consecutive terms is constant.
Check the ratios:
- 18 / 6 = 3
- 54 / 18 = 3
The ratio is
constant (3), so this is a
geometric sequence.
✔ Answer to A: This is a
geometric sequence.
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Part B: How many seeds will she plant in her 8th year?
We have a geometric sequence where:
- First term $ a = 6 $
- Common ratio $ r = 3 $
- We want the 8th term: $ a_8 $
The formula for the $ n $th term of a geometric sequence is:
$$
a_n = a \cdot r^{n-1}
$$
Plug in the values:
$$
a_8 = 6 \cdot 3^{8-1} = 6 \cdot 3^7
$$
Now calculate $ 3^7 $:
- $ 3^1 = 3 $
- $ 3^2 = 9 $
- $ 3^3 = 27 $
- $ 3^4 = 81 $
- $ 3^5 = 243 $
- $ 3^6 = 729 $
- $ 3^7 = 2187 $
Now multiply:
$$
a_8 = 6 \cdot 2187 = 13,122
$$
✔ Answer to B: She will plant
13,122 seeds in her 8th year.
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✔ Final Answers:
A) This is a
geometric sequence.
B) She will plant
13,122 seeds in her 8th year.
Parent Tip: Review the logic above to help your child master the concept of arithmetic and geometric sequences word problems worksheet.