The 4th and 7th term of an arithmetic progression are 11 and -4 respectively. What is the 15th term?

A. -49 B. -44 C. -39 D. -34 Answer: Option B
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Solution(By Apex Team)

Let the first term of an AP = a and the common difference = d 4th term of AP = A4 = a + 3d =11 ……(1) 7th term = A7 = a + 6d = -4 ……(2) Subtracting equation (1) from (2), we get : ⇒ 6d – 3d = -4 -11 ⇒ 3d = -15 ⇒ d = $\Large\frac{-15}{3}$ = -5 Substituting it in equation (1) ⇒ a = 11 – 3(-5) = 11 + 15 = 26 ∴ 15th term = A15 = a + 14d = 26 + 14(-5) = 26 – 70 = -44

A. 22
B. 25
C. 23
D. 24
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A. 5
B. 6
C. 4
D. 3
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A. -45
B. -55
C. -50
D. 0
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A. 600
B. 765
C. 640
D. 680
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