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BECE Mathematics 2012 Paper

Question : 11

Total: 40

\,\frac{2}{3}, \,\frac{5}{7}, \,\frac{2}{5}, \,\frac{1}{2}

Solution:

Concept:

To compare fractions, rewrite each fraction as an equivalent fraction with a common denominator.

Explanation:

Find the LCM of the denominators

3

7

5

, and

2

LCM

= 3 \times 7 \times 5 \times 2 = 210

Convert each fraction to an equivalent fraction with denominator

210

\frac{2}{3} = \frac{2 \times 70}{3 \times 70} = \frac{140}{210}

\frac{5}{7} = \frac{5 \times 30}{7 \times 30} = \frac{150}{210}

\frac{2}{5} = \frac{2 \times 42}{5 \times 42} = \frac{84}{210}

\frac{1}{2} = \frac{1 \times 105}{2 \times 105} = \frac{105}{210}

Now compare the numerators:

150 > 140 > 105 > 84

So the descending order is

\frac{5}{7}, \frac{2}{3}, \frac{1}{2}, \frac{2}{5}

Answer:

\frac{5}{7}, \frac{2}{3}, \frac{1}{2}, \frac{2}{5}

Therefore, the correct option is B.

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