This question tests middle school mathematics achievement, specifically finding missing terms in a sequence. Understanding sequences involves recognizing patterns such as arithmetic (adding a constant) and geometric (multiplying by a constant). These patterns allow us to determine missing terms by applying consistent rules. In the provided sequence 9, 12, __, 18, the pattern involves adding 3 to each term (12-9=3, and we need to verify 18-15=3). The correct answer is C (15) because it logically follows the pattern: 9+3=12, 12+3=15, 15+3=18. Choice A (13) is incorrect because it assumes adding only 1, while choice D (16) assumes adding 4.

This question tests middle school mathematics achievement, specifically finding missing terms in a sequence. Understanding sequences involves recognizing patterns such as arithmetic (adding a constant) and geometric (multiplying by a constant). These patterns allow us to determine missing terms by applying consistent rules. In the provided sequence 50, 40, __, 20, the pattern involves subtracting 10 from each term (50-10=40, and we need to verify with 20). The correct answer is C (30) because it logically follows the pattern: 50-10=40, 40-10=30, 30-10=20. Choice A (25) is incorrect because it assumes subtracting 15, while choice D (35) assumes subtracting only 5.

This question tests middle school mathematics achievement, specifically finding missing terms in a sequence. Understanding sequences involves recognizing patterns such as arithmetic (adding a constant) and geometric (multiplying by a constant). These patterns allow us to determine missing terms by applying consistent rules. In the provided sequence 8, 11, 14, __, the pattern involves adding 3 to each term (11-8=3, 14-11=3). The correct answer is C (17) because it logically follows the pattern: 8+3=11, 11+3=14, 14+3=17. Choice A (15) is incorrect because it assumes adding only 1, while choice D (18) assumes adding 4.

This question tests middle school mathematics achievement, specifically finding missing terms in a sequence. Understanding sequences involves recognizing patterns such as arithmetic (adding a constant) and geometric (multiplying by a constant). These patterns allow us to determine missing terms by applying consistent rules. In the provided sequence 5, 9, __, 17, the pattern involves adding 4 to each term (9-5=4, and we need to verify 17-13=4). The correct answer is C (13) because it logically follows the pattern: 5+4=9, 9+4=13, 13+4=17. Choice A (11) is incorrect because it assumes adding only 2, while choice D (14) assumes adding 5, both representing common errors in pattern recognition.

This question tests middle school mathematics achievement, specifically finding missing terms in a sequence. Understanding sequences involves recognizing patterns such as arithmetic (adding a constant) and geometric (multiplying by a constant). These patterns allow us to determine missing terms by applying consistent rules. In the provided sequence 30, 25, __, 15, the pattern involves subtracting 5 from each term (30-5=25, and we need to verify with 15). The correct answer is C (20) because it logically follows the pattern: 30-5=25, 25-5=20, 20-5=15. Choice A (18) is incorrect because it assumes subtracting 7, while choice B (19) assumes subtracting 6.