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A person is to count 4500 currency notes...

A person is to count 4500 currency notes. Let an denote the number of notes he counts in the nth minute. If `a_1=""a_2="". . . . . .""=""a_(10)=""150` and `a_(10),""a_(11),"". . . . . .` are in A.P. with common difference -2, then the time taken by him to count all notes is (1) 34 minutes (2) 125 minutes (3) 135 minutes (4) 24 minutes

A

34 minutes

B

24 minutes

C

125 minutes

D

35 minutes

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The correct Answer is:
A
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VIKAS GUPTA (BLACK BOOK) ENGLISH-SEQUENCE AND SERIES -EXERCISE (SUBJECTIVE TYPE PROBLEMS)
  1. A person is to count 4500 currency notes. Let an denote the number o...

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  2. Let a,b,c,d be four distinct real number in A.P.Then the smallest posi...

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  3. The sum of all digits of n for which sum (r =1) ^(n ) r 2 ^(r ) = 2+2^...

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  4. If lim ( n to oo) (r +2)/(2 ^(r+1) r (r+1))=1/k, then k =

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  5. The value of sum (r =1) ^(oo) (8r)/(4r ^(4) +1) is equal to :

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  6. If three non-zero distinct real numbers form an arithmatic progression...

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  7. The sum of the fourth and twelfth term of an arithmetic progression is...

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  8. In an increasing sequence of four positive integers, the first 3 terms...

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  9. The limit of (1)/(n ^(4)) sum (k =1) ^(n) k (k +2) (k +4) as n to oo i...

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  10. Which is the last digit of 1+2+3+……+ n if the last digit of 1 ^(3) + ...

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  11. There distinct positive numbers, a,b,c are in G.P. while log (c) a, lo...

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  12. The numbers 1/3, 1/3 log (x) y, 1/3 log (y) z, 1/7 log (x) x are in H...

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  13. If sum ( k =1) ^(oo) (k^(2))/(3 ^(k))=p/q, where p and q are relativel...

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  14. The sum of the terms of an infinitely decreassing Geometric Progressio...

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  15. A cricketer has to score 4500 runs. Let a (n) denotes the number of ru...

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  16. If x=10 sum(r=3) ^(100) (1)/((r ^(2) -4)), then [x]= (where [.] deno...

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  17. Let f (n)=(4n + sqrt(4n ^(2) -1))/( sqrt(2n +1 )+sqrt(2n-1)),n in N th...

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  18. Find the sum of series 1+1/2+1/3+1/4+1/6+1/8+1/9+1/12+…… oo, where the...

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  19. Let a (1), a(2), a(3),…….., a(n) be real numbers in arithmatic progres...

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  20. Let the roots of the equation 24 x ^(3) -14x ^(2) + kx +3=0 form a geo...

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  21. How many ordered pair (s) satisfy log (x ^(3) + (1)/(3) y ^(3) + (1)/(...

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