A) \[\frac{1}{15}\]
B) \[\frac{1}{5}\]
C) \[\frac{4}{15}\]
D) \[\frac{7}{15}\]
Correct Answer: C
Solution :
Let the number be x and y \[\therefore \] According to the question, x + y = 20 or x = 20 ~ y and xy = 75 \[\Rightarrow \] y (20 - y) = 75 \[\Rightarrow \] 20 y ? y2 = 75 \[\Rightarrow \]y2 - 20y + 75 = 0 \[\Rightarrow \]y2 - 15y - 5y + 75 = 0 \[\Rightarrow \]y (y - 15) - 5 (y - 15) =0 \[\Rightarrow \](y -15)(y - 5)= 0\[\Rightarrow \]y= 15 = 5 \[\therefore \] x = 5, 5 \[\therefore \,\,\,\,\frac{1}{x}+\frac{1}{y}=\frac{1}{15}+\frac{1}{5}=\frac{1+3}{15}=\]\[\frac{\mathbf{4}}{\mathbf{15}}\]
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