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okay ladies! Math time! (GET 10 POINTS!!!)

A total of 50 juniors and seniors were given a mathematics test. The 35 juniors attained an average score of 80 while the 15 seniors attained an average of 70. What was the average score for all 50 students who took the test?
(I do have the answer already- DH is studying for Compass test and the work of the problem is stumping us so please show your work so we can figure out where we are going wrong.- whoever shows the best work with correct answer gets *10 points best answer!!!) GO! :)

 
hotrodmomma

Asked by hotrodmomma at 2:01 PM on Jul. 20, 2010 in Just for Fun

Level 18 (6,309 Credits)
This question is closed.
Answers (11)
  • (35X80+15X70)/50
    DarkFaery131

    Answer by DarkFaery131 at 2:05 PM on Jul. 20, 2010

  • 77
    DarkFaery131

    Answer by DarkFaery131 at 2:04 PM on Jul. 20, 2010

  • 77?
    SuperrMommyy

    Answer by SuperrMommyy at 2:06 PM on Jul. 20, 2010

  • 35 x 80 = 2800 total points scored by the jr.s 15 x 70= 1050 total points scored by the sr.s. For a grand total of 3850 points scored. Divide that by the 50 people who took the test = 77.
    LoveMyDog

    Answer by LoveMyDog at 2:07 PM on Jul. 20, 2010

  • http://www.algebra.com/algebra/homework/Average/Average.faq.question.28831.html

    these are formulas for averages
    (total of juniors scores) / 35 = 80
    (total of seniors scores) / 15 = 70
    cross-multiply each equation
    [1] total of juniors scores = 35*80
    [2] total of seniors scores = 15*70
    ----------
    this is the formula for the whole group average
    (total of scores for both juniors and seniors) / 50 = average score
    substituting [1] & [2] from above
    average score = (35*80 + 15*70) / 50
    divide top & bottom by 5
    average score = (7*80 + 3*70) / 10
    divide top & bottom by 10
    average score = (7*8 + 3*7) / 1
    average score = 56 + 21 = 77

    KJohnson4762

    Answer by KJohnson4762 at 2:08 PM on Jul. 20, 2010

  • no idea lol
    HuskerMommy08

    Answer by HuskerMommy08 at 2:02 PM on Jul. 20, 2010

  • I have no idea but I bumped you!
    itsmesteph11

    Answer by itsmesteph11 at 2:03 PM on Jul. 20, 2010

  • Come on, I am never gonna win any points for my math skills....too bad my dh is not here, he has a masters in math...lol.
    mom2twobabes

    Answer by mom2twobabes at 2:05 PM on Jul. 20, 2010

  • 75?? 80+70=150/2=75
    Danni143

    Answer by Danni143 at 2:05 PM on Jul. 20, 2010

  • forgot to show my work LOL
    DarkFaery131

    Answer by DarkFaery131 at 2:06 PM on Jul. 20, 2010