What is the sum of the first 9 terms of an arithmetic progression if the first term is 7 and last term is 55?
A. 219
B. 279
C. 231
D. 137
Answer: Option B
Solution(By Examveda Team)
$$\eqalign{ & {S_n} = \frac{n}{2}\left( {a + l} \right) \cr & {S_9} = \frac{9}{2}\left( {7 + 55} \right) \cr & {S_9} = \frac{9}{2} \times 62 \cr & {S_9} = 9 \times 31 \cr & \,\,\,\,\,\,\,\,\, = 279 \cr} $$This Question Belongs to Arithmetic Ability >> Progressions
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Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.
A. 5
B. 6
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D. 3
E. 7
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
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