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IFoA_CAA_M0 Exam - Topic 5 Question 73 Discussion

Actual exam question for IFoA's IFoA_CAA_M0 exam
Question #: 73
Topic #: 5
[All IFoA_CAA_M0 Questions]

The first term of an arithmetic sequence is 12 and the ninth term is 68.

Calculate the sum of the first 18 terms.

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Suggested Answer: B

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Trina
3 months ago
The formula for the sum of an arithmetic sequence is S_n = n/2 * (a + l).
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Terrilyn
3 months ago
Totally agree, the sum should be around 1,287.
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Mona
3 months ago
Wait, how do we get 1,413? That seems high!
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Ronnie
4 months ago
So, the common difference is 7.
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Donte
4 months ago
The first term is 12, and the ninth term is 68.
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Lashandra
4 months ago
I feel like I should be able to calculate this, but I’m a bit confused about whether I need to find the common difference first or just jump to the sum formula.
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Cyril
4 months ago
I practiced a similar question where I had to find the sum of the first few terms, but I can't recall the exact steps for this one.
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Tequila
4 months ago
I think the formula for the sum of an arithmetic sequence is important here, but I’m not completely sure how to apply it to find the sum of the first 18 terms.
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Mable
5 months ago
I remember that to find the common difference, I need to subtract the first term from the ninth term and then divide by 8.
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Isabelle
5 months ago
Wait, what? I'm lost. How do I even start solving this? I feel like I'm missing some key information or steps. Maybe I should review the lesson on arithmetic sequences before attempting this.
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Herminia
5 months ago
No problem, I've got this! The first term is 12 and the ninth term is 68, so I can use that to find the common difference. Then it's just plugging the values into the sum formula. I'm confident I can get the right answer.
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Bettina
5 months ago
Hmm, I'm a bit unsure about this one. I remember the formula for the sum of an arithmetic sequence, but I'm not sure how to apply it with the information given. I'll have to think this through carefully.
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Royal
5 months ago
Okay, this looks like a standard arithmetic sequence problem. I'll need to find the common difference first, then use the formula for the sum of the first n terms.
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Desiree
1 year ago
I'm feeling a bit unsure about this one. Let me re-read the question and double-check my work. Hmm, I'm going to go with B) 1,287 for now, but I'm not 100% confident.
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King
1 year ago
Haha, easy peasy! This is like arithmetic sequence 101. The answer is obviously C) 1,350. Anyone who got that wrong must have been sleeping during class.
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Ronny
1 year ago
Haha, easy peasy! This is like arithmetic sequence 101. The answer is obviously C) 1,350. Anyone who got that wrong must have been sleeping during class.
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Annamae
1 year ago
D) 1,413
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Paris
1 year ago
C) 1,350
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Samuel
1 year ago
B) 1,287
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Leonida
1 year ago
A) 1,165
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Whitney
1 year ago
So the sum of the first 18 terms would be 18/2 * (12 + 68) = 18/2 * 80 = 720.
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Bernardine
1 year ago
The common difference is 8.
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Whitney
1 year ago
I think we need to find the common difference first.
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Hillary
1 year ago
This looks like a tricky one, but I think I've got it. The answer has to be D) 1,413. I double-checked my work, and that's the only one that makes sense.
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Bobbye
1 year ago
Great job! D) 1,413 is the correct answer for the sum of the first 18 terms.
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Rebbecca
1 year ago
I agree, I also got D) 1,413 as the sum of the first 18 terms.
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Ashlee
1 year ago
I think you're right, the answer is D) 1,413.
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Lorita
1 year ago
I'm pretty sure the answer is B) 1,287. The common difference is 7, and the sum of the first 18 terms is the classic arithmetic sequence formula.
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Dominic
1 year ago
Okay, let's think this through step-by-step. The first term is 12 and the ninth term is 68. We need to find the common difference and then use the formula for the sum of an arithmetic sequence.
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Malcom
1 year ago
Great job! That's the correct answer. Arithmetic sequences can be tricky, but you nailed it.
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Virgie
1 year ago
Sum of the first 18 terms is 1,287. So, the answer is B) 1,287.
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Ming
1 year ago
Common difference is 8. Now use the formula for the sum of an arithmetic sequence.
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Cathrine
1 year ago
Find the common difference by subtracting the first term from the ninth term.
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Rutha
1 year ago
Then, we use the formula for the sum of an arithmetic sequence. The answer is 1,287.
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Jose
1 year ago
First, let's find the common difference. It's 8.
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