Question : Evaluate: $\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}+\frac{1}{143}$
Option 1: $\frac{4}{39}$
Option 2: $\frac{5}{39}$
Option 3: $\frac{10}{39}$
Option 4: $\frac{7}{39}$
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Correct Answer: $\frac{5}{39}$
Solution :
$\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}+\frac{1}{143}$ $=\frac{1}{(3×5)}+\frac{1}{(5×7)}+\frac{1}{(7×9)}+\frac{1}{(9×11)}+\frac{1}{(11×13)}$ $= \frac{1}{2}×[( \frac{1}{3}− \frac{1}{5})+( \frac{1}{5}− \frac{1}{7})+( \frac{1}{7}− \frac{1}{9})+( \frac{1}{9}− \frac{1}{11})+( \frac{1}{11}− \frac{1}{13})]$ $= \frac{1}{2}×( \frac{1}{3}− \frac{1}{13})$ $= \frac{1}{2}×( \frac{13-3}{39})$ $= \frac{5}{39}$ Hence, the correct answer is $ \frac{5}{39}$.
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Question : Simplify the following expression. $\frac{7}{10} \div \frac{3}{7}$ of $\left(2 \frac{3}{10}+2 \frac{3}{5}\right)+\frac{1}{5} \div 1 \frac{2}{5}-\frac{2}{7}$
Option 1: $-\frac{4}{21}$
Option 2: $\frac{5}{21}$
Option 3: $\frac{4}{21}$
Option 4: $-\frac{5}{21}$
Question : Let $x=\frac{5 \frac{3}{4}-\frac{3}{7} \times 15 \frac{3}{4}+2 \frac{2}{35} \div 1 \frac{11}{25}}{\frac{3}{4} \div 5 \frac{1}{4}+5 \frac{3}{5} \div 3 \frac{4}{15}}$. When $y$ is added to $x$, the result is $\frac{7}{13}$. What is the value of $y$?
Option 1: $\frac{1}{13}$
Option 2: $\frac{9}{13}$
Option 3: $\frac{2}{13}$
Option 4: $\frac{4}{13}$
Question : If $3\sqrt{\frac{1-a}{a}}+9=19-3\sqrt{\frac{a}{1-a}};$ then, what is the value of $a?$
Option 1: $\frac{3}{10}$ and $\frac{7}{10}$
Option 2: $\frac{1}{10}$ and $\frac{9}{10}$
Option 3: $\frac{2}{5}$ and $\frac{3}{5}$
Option 4: $\frac{1}{5}$ and $\frac{4}{5}$
Question : Find the fraction which bears the same ratio to $\frac{1}{27}$ that $\frac{3}{7}$ does to $\frac{5}{9}$.
Option 1: $\frac{5}{9}$
Option 2: $\frac{1}{35}$
Option 3: $\frac{45}{7}$
Option 4: $\frac{7}{45}$
Question : The value of $1 \frac{3}{4}+1 \frac{5}{7} \div 2 \frac{3}{7} \times 2 \frac{3}{7}=$?
Option 1: $1 \frac{11}{28}$
Option 2: $2 \frac{13}{28}$
Option 3: $3 \frac{13}{28}$
Option 4: $4 \frac{23}{28}$
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