Question

Difficulty: MediumFractions, Decimals, Percentages, and Approximations

What is the value of the expression 0.00048×0.0250.0016\frac{0.00048 \times 0.025}{0.0016} expressed in standard form?

  1. 7.5×1037.5 \times 10^{-3}Answer
  2. B
    7.5×1027.5 \times 10^{-2}
  3. C
    7.5×1047.5 \times 10^{-4}
  4. D
    1.2×1021.2 \times 10^{-2}

Answer

7.5×1037.5 \times 10^{-3}
The expression evaluates step-by-step to 0.75×1020.75 \times 10^{-2}, which when written in standard form A×10nA \times 10^n (where 1A<101 \le A < 10) gives 7.5×1037.5 \times 10^{-3}.

Step-by-Step Solution

1
Convert each decimal in the expression to standard form (powers of 10).
0.00048=4.8×1040.00048 = 4.8 \times 10^{-4}, 0.025=2.5×1020.025 = 2.5 \times 10^{-2}, and 0.0016=1.6×1030.0016 = 1.6 \times 10^{-3}.
Converting decimals into standard form simplifies multiplication and division using laws of indices.
2
Simplify the numerator.
(4.8×104)×(2.5×102)=(4.8×2.5)×104+(2)=12×106=1.2×105(4.8 \times 10^{-4}) \times (2.5 \times 10^{-2}) = (4.8 \times 2.5) \times 10^{-4 + (-2)} = 12 \times 10^{-6} = 1.2 \times 10^{-5}.
Multiply the numerical coefficients together and add the exponents of 10.
3
Divide the numerator by the denominator.
1.2×1051.6×103=(1.21.6)×105(3)=0.75×102\frac{1.2 \times 10^{-5}}{1.6 \times 10^{-3}} = \left(\frac{1.2}{1.6}\right) \times 10^{-5 - (-3)} = 0.75 \times 10^{-2}.
Divide the coefficients and subtract the exponent of the denominator from that of the numerator.
4
Convert the result into standard form (A×10nA \times 10^n where 1A<101 \le A < 10).
0.75×102=(7.5×101)×102=7.5×1030.75 \times 10^{-2} = (7.5 \times 10^{-1}) \times 10^{-2} = 7.5 \times 10^{-3}.
Standard form requires the leading coefficient to be between 1 and 10.

Key Concept

Fractions, Decimals, and Standard Form Conversions
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