Question

You have 42 minutes to take an exam of 28 questions. After you finish the first 12 ques- tions, you realize you must answer the re- maining questions twice as fast to finish the exam.
How many questions per minute were you answering?
Answer in units of questions/minute

Answer 1

Suppose you answered the first 12 questions on average with a rate of x minutes/question.

Hence for the first 12 questions, you've consumed 12x minutes.

Then for the next 16 questions you must answer at a rate of x/2. Hence with a time of
\[ 16 \frac{x}{2} = 8x \]

Now those two times added together must be 42 minutes. Use those facts to solve for x.

Answer 2

thank you!

Answer 3

Notice that x is in units of minutes/question.

Once you've found x, you will need to take its reciprocal to give the answer in the form asked in the question: questions/minute.