prernamalhotra wrote:Is there an easy way to solve this question:
Q.What is 1/(1)(2)+1/(2)(3)+1/(3)(4)+1/(4)(5)+1/(5)(6)+1/(6)(7)+1/(7)(8)+1/(8)(9)+1/(9)(10)?
1) 2/5
2) 3/5
3) 7/10
4) 46/55
5) 9/10
WRITE IT OUT and LOOK FOR A PATTERN.
Sum of the first 2 terms:
1/2 + 1/6 = 2/3.
Sum of the first 3 terms:
2/3 + 1/12 = 3/4.
Sum of the first 4 terms:
3/4 + 1/20 = 4/5.
In each case:
The NUMERATOR of the sum = the NUMBER OF TERMS.
THE DENOMINATOR of the sum = NUMERATOR + 1.
The given sum is composed of 9 terms.
Sum of the first 9 terms = 9/10.
The correct answer is
E.
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