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 BShow Answer
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
Related Questions On Progressions
How many terms are there in 20, 25, 30 . . . . . . 140?
A. 22B. 25
C. 23
D. 24
Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.
A. 5B. 6
C. 4
D. 3
Find the 15th term of the sequence 20, 15, 10 . . .
A. -45B. -55
C. -50
D. 0
The sum of the first 16 terms of an AP whose first term and third term are 5 and 15 respectively is
A. 600B. 765
C. 640
D. 680
HI 
EN