95. The sum of the terms of a geometric progression is 2047. Find the common ratio.
(1) The first and last terms of the series are 1 and 1024 respectively.
(2) Last but one term of the series is 512.
How would you approach this problem?
(arn - 1)/ (r-1) = 2047 ....(1)
Statement (1)
The first and last terms of the series are 1 and 1024 respectively.
a = 1 and arn-1 = 1024
rn-1 = 1024.....(2)
Solving (1) and (2), we can find r; SUFFICIENT
Statement (2)
Last but one term of the series is 512.
arn-2 = 512.....(3)
Even after solving (1) and (3), we will be left with 2 variables - r and n; NOT SUFFICIENT.
The correct answer is A;
statement 1 alone is suffici
(1) The first and last terms of the series are 1 and 1024 respectively.
(2) Last but one term of the series is 512.
How would you approach this problem?
(arn - 1)/ (r-1) = 2047 ....(1)
Statement (1)
The first and last terms of the series are 1 and 1024 respectively.
a = 1 and arn-1 = 1024
rn-1 = 1024.....(2)
Solving (1) and (2), we can find r; SUFFICIENT
Statement (2)
Last but one term of the series is 512.
arn-2 = 512.....(3)
Even after solving (1) and (3), we will be left with 2 variables - r and n; NOT SUFFICIENT.
The correct answer is A;
statement 1 alone is suffici
