A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

AndrewKaiser333

  • one year ago

Joe's test grades in History class are: 92%, 89%, 85%, 89%, and 90. The semester final will count as two tests. Joe needs to get a grade of 90% or higher for the semester to get an A. What is the minimum score Joe can get on the final test and average 90%?

  • This Question is Closed
  1. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    How do you find the average grade of several grades?

  2. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    can you look it up i am stumped i was gone from school for several days due to the death of my mom

  3. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I tried and i found nothing i am not sure what you look for first

  4. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    To find the average of several grades, add up all the grades, and divide by the number of grades.

  5. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok can you start the equation?

  6. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    You are given these test grades: 92, 89, 85, 89, 90 He will take a final exam and get one more grade that counts like two tests. Since we don't know what his final exam grade is, we call it x.

  7. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    That means the sum off all the grades will be: \(92+ 89+ 85+ 89+ 90 +x + x\) Ok so far?

  8. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok

  9. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    To find the average, you divide the sum of the grades by the number of grades. There are 7 grades altogether, so to find the average, we divide the sum by 7. \(\dfrac{92+ 89+ 85+ 89+ 90 +x + x}{7}\) Ok?

  10. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    k

  11. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    We want the average to be 90 or more, so we now set it up as an inequality: \(\dfrac{92+ 89+ 85+ 89+ 90 +x + x}{7} \ge 90\)

  12. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Now we need to solve the inequality for x.

  13. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    k

  14. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    First, add all the numbers on the numerator of the fraction. Also, what is x + x = ?

  15. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\frac{ 445+2x }{ 7 }\

  16. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\frac{ 445+2x }{ 7 }\]

  17. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes?

  18. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Great, so now we have this: \(\dfrac{445 +2x}{7} \ge 90\)

  19. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    now x7

  20. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Correct. Now multiply both sides by 7 to get rid of the denominator of 7. \(7 \times \dfrac{445 +2x}{7} \ge 7 \times 90\)

  21. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    630

  22. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    445+2x >630

  23. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    -445

  24. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    2x>185

  25. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \(\cancel{7} \times \dfrac{445 +2x}{\cancel{7}~1} \ge 630\) \(445 + 2x \ge 630\) Now subtract 445 from both sides.

  26. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    /2

  27. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Correct. Now divide both sides by 2.

  28. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    92.5>x

  29. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    No. Be careful. Don't switch sides.

  30. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    oops

  31. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    how is it done then

  32. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    x>92.5

  33. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    We had \(2x \ge 185\) Divide both sides by 2: \(\dfrac{2x}{2} \ge \dfrac{185}{2}\) We get: \(x \ge 92.5\)

  34. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok

  35. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Correct, but remember it's "greater than or equal", not just plain "greater than."

  36. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    thanks i see now

  37. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes i know

  38. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    my keys just won't let me click to do it the way you did it

  39. AndrewKaiser333
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    it stopped working for some reason

  40. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Since the answer is \(x \ge 92.5\) That means as long as he gets at least 92.5% on the semester exam, he will have an 90% average, meaning he gets an A grade.

  41. mathstudent55
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    You're welcome.

  42. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.