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SSC Selection Post 2019 PYQ — Question 57

SSC Selection Post - Higher Secondary Level 2019 - 15 Oct 2019 • Quantitative Aptitude • Q57

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What is the value of 130.31+131.32+132.33+....+189.90{1 \over 30.31} + {1 \over 31.32} + {1 \over 32.33} +....+ {1 \over 89.90}  ?

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Correct answer: A

Explanation

The correct answer is option 1 i.e.  145{1 \over 45}.

1n(n+1)=1n−1n+1\frac{1}{n(n+1)} = \frac{1}{n} - \frac{1}{n + 1}

From the given expression,

⇒ 130−131+131−!32....188−189+189−190\frac{1}{30} - \frac{1}{31} + \frac{1}{31} - \frac{!}{32} . ...\frac{1}{88} - \frac{1}{89} + \frac{1}{89} - \frac{1}{90}

⇒ 130−190\frac{1}{30} - \frac{1}{90} = 145\frac{1}{45}