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The sum of an A.P. is 1 and the nth term...

The sum of an A.P. is 1 and the `nth` term is 20. If `S_(n)=399`, then `n=…..`

A

42

B

38

C

21

D

19

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The correct Answer is:
B
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NAVNEET PUBLICATION - MAHARASHTRA BOARD-ARITHMETIC PROGESSION -PRACTICE SET 3.4
  1. For an A.P. if t(7)=4.d=-4.then a=…..

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  2. For an A.P. if a=3.5,d=0,n=101, then t(n)=….

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  3. The 21st term of an AP whose first two terms are -3 and 4, is

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  4. If for an A.P.,d=5, then t(18)-t(13)=….

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  5. The sum of first five multiples of 3 is

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  6. The sum of the first ten terms of the A.P.15,10,5,….is……

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  7. The sum of an A.P. is 1 and the nth term is 20. If S(n)=399, then n=…....

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  8. The 4th term from the end of an AP -11, -8, -5, …, 49 is

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  9. The sun of the 5th and the 7th terms of an AP is 52 and the 10th term ...

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  10. Find the sum of the first ten terms of the A.P. whose 4th term is -15 ...

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  11. Two A.P's are given 9,7,5..and 24,21,18,….If n^(th)term of both the pr...

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  12. If sum of the 3rd and the 8th terms of an AP is 7 and the sum of the 7...

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  13. In an A.P., first term is -5 and last term is 45. If sum of all the nu...

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  14. Sum of 1 to n natural numbers is 36, then find the value of n.

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  15. Split 207 into three parts such that these are in A.P. and the product...

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  16. An AP consists of 37 terms. The sum of the three middle most terms is ...

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  17. Show that the sum of an AP whose first term is a, the second term b an...

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

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  19. If m times the mth term of an AP is equal to n times its nth term, the...

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  20. Rs. 1000 is deposited at 10 per cent simple interest. Check if the int...

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