Answer:
78
Step-by-step explanation:
The number of correct problems is found by multiplying the percentage that were correct by the total number of problems.
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number correct = fraction correct × number of problems
number correct = 0.39 × 200 = 78
Serenity answered 78 problems correctly.
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Additional comment
The symbol % is fully equivalent to /100. That is 39% = 39/100 = 0.39 (pronounced "thirty-nine hundredths"). Using a percent symbol is just another way to write a fraction.
