ssccglapex

If 7th and 13th terms of an A.P. be 34 and 64 respectively, then its 18th term is

A. 87 B. 88 C. 89 D. 90 Answer: Option C
Show Answer

Solution(By Apex Team)

$\begin{array}{l}\text{7th term (a7) = a + 6d = 34}\\ \text{13th term (a13) = a + 12d = 64}\\ \text{Subtracting, 6d = 30 ⇒ d = 5}\\ \text{and a + 12 x 5 = 64}\\ \text{⇒ a + 60 = 64}\\ \text{⇒ a = 64 – 60 = 4}\\ \text{18th term (a18)}\\ \text{= a + 17d}\\ \text{= 4 + 17 x 5}\\ \text{= 4 + 85}\\ \text{= 89}\end{array}$

Related Questions On Progressions


How many terms are there in 20, 25, 30 . . . . . . 140?

A. 22
B. 25
C. 23
D. 24
Show Answer

Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.

A. 5
B. 6
C. 4
D. 3
Show Answer

Find the 15th term of the sequence 20, 15, 10 . . .

A. -45
B. -55
C. -50
D. 0
Show Answer

The sum of the first 16 terms of an AP whose first term and third term are 5 and 15 respectively is

A. 600
B. 765
C. 640
D. 680
Show Answer



More Related Questions On Progressions