If 1 + (1/2) + (1/3) + … + (1/20) = k, then what is the value of (1/4) + (1/6) + (1/8) + … + (1/40)?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. (k - 1)/2
1 + (1/2) + (1/3) + .... (1/20) = k
1/2 + 1/3 + .....1/20 = k - 1
1/2(1/2 + 1/3 + .....1/20) = (k - 1)/2
1/4 + 1/6 + 1/8 +.....1/40 = (k - 1)/2