Question

Error Analysis  Your friend says that the product of 1.4 times 10 Superscript 9 and 5 times 10 Superscript negative 6 is 7 times 10 Superscript negative 3. What is the correct​ product? What mistake did your friend likely​ make?
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Part 1
left parenthesis 1.4 times 10 Superscript 9 right parenthesis left parenthesis 5 times 10 Superscript negative 6 right parenthesisequals
  
7 times 10 cubed
​(Use scientific notation. Use the multiplication symbol in the math palette as​ needed.)
Part 2
What mistake did your friend likely​ make?
A.
Your friend incorrectly calculated the exponent of the product.
B.
Your friend subtracted the exponents instead of adding.
C.
Your friend added the numbers instead of multiplying.
D.
Your friend multiplied the exponents instead of adding.

Answer 1

(1.4 × 10^9)(5 × 10^-6) = (1.4·5) × 10^(9 + (-6)) = 7 × 10^3.

Your friend likely miscalculated the exponent (they ended up with −3 instead of 3), so choice A.