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How many terms are there in the GP 5, 20, 80, 320........... 20480?

A. 5

B. 6

C. 8

D. 9

E. 7

Answer: Option E

Solution(By Examveda Team)

Common ratio, r = $$\frac{{20}}{5}$$ = 4
Last term or nth term of GP = arn - 1
20480 = 5 × (4n - 1)
Or, 4n - 1 = $$\frac{{20480}}{5}$$  = 48
So, comparing the power,
Thus, n - 1 = 8
Or, n = 7
Number of terms = 7

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Comments ( 4 )

  1. AMIT CHAUDHARY
    AMIT CHAUDHARY :
    2 months ago

    4 to the power 6 = 4096

  2. Shubham Singh
    Shubham Singh :
    2 years ago

    Take 4^6 and then solve

  3. Snjay KumR
    Snjay KumR :
    2 years ago

    20480 devide by 5 then we get 4096 if we multiple 4 by 6 times then we get the correct answer and answer is 7 how

  4. Siva Rama
    Siva Rama :
    3 years ago

    4^6=4096
    4^6=4^(n-1)
    n-1=6
    N=7

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