Maria got 84% correct, so she got 16% of the questions wrong. If you understand percentages, you'll know that you can multiply 0.16 and 25 to get 16% of 25, which is 4. So she got 4 problems wrong. If you don't understand this, you can use ratios. Set up a proportion to solve instead:
[tex] \frac{Number Wrong}{Total Problems} = \frac{Percentage of Questions Wrong}{Total Percentage of Questions} \\
\frac{x}{25} = \frac{16}{100} \\
x= \frac{16}{4} \\
x=4 [/tex]
So Maria got 4 questions wrong.
