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The sum of the first fifteen terms of an...

The sum of the first fifteen terms of an A.P. is 105 and the sum of the next fifteen terms is 780. Find the common difference of A.P.:

A

4

B

3

C

6

D

5

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The correct Answer is:
B
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QUANTUM CAT-SEQUENCE, SERIES & PROGRESSIONS-QUESTION BANK
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  2. If m times the mth term of an A.P. is equal to n times its nth term, f...

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  3. The sum of the first fifteen terms of an A.P. is 105 and the sum of th...

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  4. If the first term of an AP is 2 and the sum of the first five terms i...

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  5. The sum of the first six terms of an A.P. is 42. The ratio of the 10th...

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  6. (i) The sum of n terms of two arithmetic series are in the ratio of (7...

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  7. The sum of three numbers in AP is 15 and sum of their squares is 93 fi...

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  8. If the nth term of an A.P. is 4n-1 , find the 30th term and the sum of...

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  9. The sum of n terms of a series is 3n^2+5n find the value of n if nth ...

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  10. Find the number of terms of the A.P. 98,91,84,…must be taken to give a...

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  11. What is the greatest possible sum of the A.P. 17,14,11,…

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  12. What is the least possible sum of the A.P. -23,-19 , -15 , … :

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  13. Find the sum of all odd numbers of four digits which are divisible by ...

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  14. If a,b,c be the pth , qth and rth terms of an A.P., then p(b-c) + q(c-...

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  15. If a,b,c be respectively the sum of first p,q,r terms of an A.P. then ...

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  16. Divide 20 into four parts which are in A.P. and such that the product ...

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  17. The sum of first p- terms terms of an A.P. is q and the sum of first q...

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  18. Find the 6th term of the sequence 2,10,50,250,…..

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  19. Find the sum of the first 6 terms of the G.P. 3, 9/2 , (27)/(4) ,(8...

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  20. Find the sum of first five terms of the G.P 5,15,45…..

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