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anonymous

  • one year ago

Class has 50 question test, each correct answer is 2 pt, each wrong is -.5, if no answer then no points. If student needs to earn 70 pt on the test then what is the equation in terms of incorrect answers

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  1. triciaal
    • one year ago
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    number correct = x number incorrect = 50-x when all correct x = 50 ; points = 100 when all incorrect 50*(-0.5) = -25 points to get 70 points 2x -0.5(50-x)= 70

  2. anonymous
    • one year ago
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    so you dont solve for x but state its 50?

  3. triciaal
    • one year ago
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    |dw:1444105732138:dw|

  4. triciaal
    • one year ago
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    the number of test question = 50

  5. anonymous
    • one year ago
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    if you put in 50 for x then its 2x-.5(0)? which is 100 if you replace x with 50

  6. DN_20
    • one year ago
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    So if 50 questions are all correct, then 50 (2) = 100 if 50 questions are all wrong, then 50 (-.5) = -25 So x = # of right questions, y = # of wrong questions 2x -.5y = 70 MY number I will say you will need x=38 and y =12 plug in 2 (38) - .5 (12) = 70 76 - 6 = 70 So the student needs at least 38 right and 12 wrong to get 70 points

  7. anonymous
    • one year ago
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    DN_20 how did you know to use 38 and 12?

  8. DN_20
    • one year ago
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    So let see: (1)2x -.5y = 70 (2)x + y = 50 Multiply the (1) by 2 4x - y = 140 x +y = 50 Eliminate y, add the rest 5x = 190 x = 38 Plug in x: 38 +y = 50 y= 12 There we go!!!!!!

  9. anonymous
    • one year ago
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    looks great. but what is the equation in terms of incorrect answers. Shouldnt it be equal to 30 not 70 to focus on incorrect possibles?

  10. DN_20
    • one year ago
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    Ok, so this is just the same: (1)2x -.5y = 30 (2)x + y =50 So the same, you multiply (1) by 2 So 4x - y = 60 x+y = 50 Eliminate y, add the others: 5x = 110 x = 22 So y = 50 -22 =28 They will need 16 correct and 34 wrong 2 (22) -.5 (28)= 44-14= 30 There.

  11. DN_20
    • one year ago
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    x = 22 and y = 28

  12. anonymous
    • one year ago
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    Thank you

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