math!

You have 48 minutes to take an exam of 21 questions. After you finish the first 10 questions, you realize you must answer the remaining questions twice as fast to finish the exam.

How many questions per minute were you answering?

Also, how many questions per minute must you now answer to finish the exam on time?

  1. 0
  2. 0
  3. 13
asked by Lewis
  1. q = first questions/min
    2 q = final que/min

    t min for first ten
    48 - t min for final 11

    q t = 10 so t = 10/q

    q t + 2q(48-t) = 21
    10 + 96q - 20 = 21
    96 q = 31
    q = 31/96 questions/min
    so twice that = 62/96 to finish
    ========================
    check
    t = 960/31 = 30.97 min
    48-t = 17.03 min

    30.97 * 31/96 = 10
    17.03 * 62/96 = 11
    sum = 21 sure enough

    1. 0
    2. 0
    posted by Damon

Respond to this Question

First Name

Your Response

Similar Questions

  1. Algebra 2

    You have 48 minutes to take an exam of 21 questions. After you finish the first 10 questions, you realize you must answer the remaining questions twice as fast to finish the exam. How many questions per minute were you answering?

    asked by Lewis on November 23, 2016
  2. statistics

    The time to complete a standardized exam is approximately normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the 68-95-99.7 rule, if students are given 90 minutes to complete the exam, what percentage

    asked by abby on April 13, 2010
  3. Math

    The time needed to complete a final examination in a particular college course is normally distributed with a mean of 83 minutes and a standard deviation of 13 minutes. Answer the following questions. What is the probability of

    asked by Kelsey on October 23, 2015
  4. Probability (Pre-Calculus)

    A class is given a list of eight study problems from which five will be part of an upcoming exam. If a given student knows how to solve six of these problems, find the probability that the student will be able to answer: (a) all

    asked by Hailey on March 26, 2010
  5. English

    1. which of the following sentences is grammatically correct? A. The student wrote too slow to finish the exam, but he has always been a slowly writer. B. The student wrote too slow to finish the exam, but he has always been a

    asked by rips2309 on May 22, 2017
  6. ap english exam

    Does anyone know where I can find a free online copy of questions 28-43 on the 1996 AP English Language & Composition Exam? I found the exam but for some reason they skipped questions 28-43. I couldn't find it online, but it's

    asked by Anonymous on November 16, 2006
  7. English

    1)which of the following sentences is grammatically correct? A. The student wrote too slow to finish the exam, but he has always been a slowly writer. B. The student wrote too slow to finish the exam, but he has always been a slow

    asked by pal0893 on May 15, 2017
  8. math

    The time required to finish a test in normally distributed with a mean of 80 minutes and a standard deviation of 15 minutes. What is the probability that a student chosen at random will finish the test in more than 110 minutes?

    asked by chelsa on May 31, 2011
  9. Math

    The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test between 24 and 48 minutes?

    asked by Destiny on June 1, 2015
  10. Math

    According to these data, the mean time students spent on the exam was 94.1 minutes, and the standard deviation was 24.23 minutes. Suppose the exam proctor realized after compiling these data that he had used the wrong start time

    asked by Marquita on October 12, 2017

More Similar Questions