Arithmetic and geometric sequences
Lesson 5 of 20 in Union Aptitude Prep. The start plays free here.
- A row of numbers
- A pattern to find
- A next number to choose
- 4 → 7 → 10 → 13
- Common difference: +3
- Next: 13 + 3 = 16
- 3 → 6 → 12 → 24
- Common ratio: ×2
- Next: 24 × 2 = 48
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How the lesson starts
You see a row of numbers and a question: what comes next? Number patterns like this appear in the official Algebra and Functions sample.
Your practice row reads 4, 7, 10, 13. Subtract each number from the next. The difference stays at 3. That makes this an arithmetic sequence.
Then, in the full lesson
- Add again
- Same ratio
- Multiply again
- 2 questions along the way
A question from this lesson
Your practice row is 23, 19, 15. Keep the common difference. What comes next?
- 11
- 15
- 19
Show the answer
A. 11. 11 continues the common difference of −4. Choosing 15 repeats the last term. Choosing 19 adds 4 instead of subtracting 4.
The full class, $39 once.
Paid once, no subscription. Ask for a refund within 7 days of buying if you’ve done less than 25% of the class.
- Number series trainer
- Algebra & functions with worked steps
- Reading comprehension sets
Not affiliated with IBEW, NECA, ETA or any JATC. Original practice questions only.