GED Mathematical Reasoning TestQuantitative Problem Solving with Rational NumbersHard
A city's annual budget is $2.5 x 10^8. If 15% of the budget is allocated to public safety, how much money, in dollars, is allocated to public safety?
- A$3.75 x 10^9
- B$3.75 x 10^8
- C$3.75 x 10^6
- D$3.75 x 10^7
Show answer & explanationAnswer & explanation
Correct answer: D. $3.75 x 10^7
To find 15% of $2.5 x 10^8, first convert 15% to a decimal (0.15). Then, multiply 0.15 by 2.5 x 10^8. (0.15 * 2.5) x 10^8 = 0.375 x 10^8. To express this in proper scientific notation, adjust to 3.75 x 10^7.
Why the other options are wrong
- A. This is significantly incorrect; the power of 10 is much too large.
- B. This is incorrect; the power of 10 is too large, possibly from incorrect decimal shift.
- C. This is incorrect; the power of 10 is too small, possibly from incorrect decimal shift.
Percentage of Number in Scientific Notation
To calculate a percentage of a number expressed in scientific notation, convert the percentage to a decimal, then multiply the decimal by the coefficient of the scientific notation number, keeping the power of 10 consistent, and finally adjust to proper scientific notation if needed.
- Convert percentage to decimal (e.g., 15% = 0.15).
- Multiply the decimal by the coefficient of the scientific notation.
- Adjust the coefficient and exponent to maintain proper scientific notation (coefficient between 1 and 10).
Memory trick: Percent becomes decimal, multiply by number, then adjust the power.