Question

Difficulty: HardExponents, Roots, and Scientific Notation

What is the value of the expression below?

2.7×10731.6×1092.5×101\frac{\sqrt[3]{2.7 \times 10^7} \cdot \sqrt{1.6 \times 10^9}}{\sqrt{2.5 \times 10^{-1}}}
  1. A
    2.4×1062.4 \times 10^6
  2. B
    6.0×1066.0 \times 10^6
  3. C
    1.2×1071.2 \times 10^7
  4. 2.4×1072.4 \times 10^7Answer
  5. E
    2.4×1092.4 \times 10^9

Answer

The correct value of the expression is 2.4×1072.4 \times 10^7.
Evaluating the terms step-by-step, the first term in the numerator simplifies to 3×1023 \times 10^2 and the second term simplifies to 4×1044 \times 10^4. Multiplying these values results in 1.2×1071.2 \times 10^7. The denominator evaluates to 0.50.5. Dividing 1.2×1071.2 \times 10^7 by 0.50.5 yields 2.4×1072.4 \times 10^7.

Step-by-Step Solution

1
Simplify the first term in the numerator: 2.7×1073\sqrt[3]{2.7 \times 10^7}.
3×1023 \times 10^2
Rewrite 2.7×1072.7 \times 10^7 as 27×10627 \times 10^6. Since 27 is a perfect cube (333^3) and 10610^6 is a perfect cube ((102)3(10^2)^3), the cube root is 3×1023 \times 10^2.
2
Simplify the second term in the numerator: 1.6×109\sqrt{1.6 \times 10^9}.
4×1044 \times 10^4
Rewrite 1.6×1091.6 \times 10^9 as 16×10816 \times 10^8. Since 16 is a perfect square (424^2) and 10810^8 is a perfect square ((104)2(10^4)^2), the square root is 4×1044 \times 10^4.
3
Multiply the simplified numerator terms.
1.2×1071.2 \times 10^7
Multiply the coefficients and add the exponents: (3×102)×(4×104)=(3×4)×102+4=12×106=1.2×107(3 \times 10^2) \times (4 \times 10^4) = (3 \times 4) \times 10^{2+4} = 12 \times 10^6 = 1.2 \times 10^7.
4
Simplify the denominator: 2.5×101\sqrt{2.5 \times 10^{-1}}.
5×1015 \times 10^{-1} (or 0.50.5)
Rewrite 2.5×1012.5 \times 10^{-1} as 0.250.25, or as 25×10225 \times 10^{-2}. The square root is 25×102=5×101=0.5\sqrt{25} \times \sqrt{10^{-2}} = 5 \times 10^{-1} = 0.5.
5
Divide the numerator by the denominator.
2.4×1072.4 \times 10^7
Divide 1.2×1071.2 \times 10^7 by 0.50.5 to get 2.4×1072.4 \times 10^7. In scientific notation terms: 1.2×1075×101=0.24×108=2.4×107\frac{1.2 \times 10^7}{5 \times 10^{-1}} = 0.24 \times 10^8 = 2.4 \times 10^7.

Key Concept

Evaluating calculations involving square and cube roots of scientific notation expressions by adjusting decimal places to construct perfect powers.
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