JAMB Mathematics 2013 Paper

Concept:Use powers of ten to simplify decimal multiplication and division, then round correctly.Explanation:Rewrite each decimal using powers of ten: $1.25 = 125 \times 10^{-2}$, $0.025 = 25 \times 10^{-3}$, and $0.05 = 5 \times 10^{-2}$. Substitute into the expression: $$\frac{1.25 \times 0.025}{0.05} = \frac{125 \times 10^{-2} \times 25 \times 10^{-3}}{5 \times 10^{-2}}$$ Group the numbers and powers of ten: $$\frac{125 \times 25}{5} \times 10^{-2 - 3 + 2}$$ Simplify the coefficient: $\frac{125 \times 25}{5} = 125 \times 5 = 625$. Simplify the exponent: $10^{-2 - 3 + 2} = 10^{-3}$. So the exact value is $625 \times 10^{-3} = 0.625$. To round to $1$ decimal place, look at the second decimal digit, which is $2$. Since $2 < 5$, keep the first decimal digit unchanged: $0.625 \approx 0.6$.Answer:$0.6$ Correct option: A.