C. DETERMINING ARITHMETIC MEANS, NTH TERM OF AN ARITHMETIC SEQUENCE AND SUM OF THE TERMS OF A GIVEN ARITHMETIC SEQUENCE 11. Determine the arithmetic mean between -23 and 7 A. 8 B. 6 C.-6 D. -8 12. If three arithmetic means are to be inserted between 3 and 63, what is the second arithmetic mean? A. 15 B. 18 13. Find the arithmetic mean between 7 and 39. A. 16 14. In the arithmetic A. 98th term B. 23 C. 33 C. 32 sequence 5, 9, 13, 17, which term is 405? B. 99th term C. 100th term D. 48 D. 113 D. 101st term 15. Which of the following is the 43rd term of the arithmetic sequence 3, 0, -3, ...? A. -117 B. -120 C. -123 D. -126 16. What are the first and the last terms of an arithmetic sequence if its arithmetic means are -5, -9, and-13? A. -1 and 17 B. -1 and -16 C. -2 and 16 17. What is the 25th term of the arithmetic sequence 4.9, 5.2, 5.5, 5.8,...? A.-2.6 B. 11.8 C. 12.1 D.1 and -17 D. 76.2 18. How many terms are there in an arithmetic sequence with a common difference of 4 and with first and last torme. -10 and-3 rocnactively? A. 7 B. 6 C. 5 D. 4 19. Find the sum of the first 18 terms of the arithmetic series, 15+19+23+27 + A 874 B 878 C 882 D. 890 20. Find the sum of the first 15 terms of the arithmetic series if the first term is 3 and the 15th term 85. A. 680 B. 675 C. 670 D. 660​