InterviewSolution
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InterviewSolution
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consider an infinite geometric series with first term `a` and comman ratio `r` if the sum is `4` and the second term is `3/4` then find `a&r`A. `a = 4//7, r= 3//7`B. `a = 2, r = 3//8`C. `a = 3//2, r = 1//2`D. `a = 3, r =1//4` |
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Answer» Correct Answer - D Since, sum = 4 and second term `= (3)/(4)` It is given first term a and common ratio r `rArr (alpha)/(1-r) = 4, alphar = (3)/(4)` `rArr r = (3)/(4alpha)` `rArr (alpha)/(1 - (3)/(4 alpha)) = 4` `rArr (4 alpha^(2))/(4alpha -3) = 4` `rArr (alpha -1) (alpha -3) = 0` `rArr alpha = 1 or 3` When `alpha = 1, r = 3//4` and when `alpha = 3, r = 1//4` |
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