+0

# Help me :)

+1
827
6

Help Me :) I hope you can read this...

Nov 15, 2017

#5
+5

total number of points  =  ( 2 * number correct ) - ( 0.5 * number incorrect )

a.     score   =   ( 2 * 30 ) - ( 0.5 * 5 )   =   60 - 2.5   =   57.5

b.     No, you must know the number correct and the number incorrect to determine the score.

c.     We want to set the score equal to  80  and solve for the number incorrect.

Also...let's say  c = number correct  and  w = number incorrect

80  =  2c - 0.5w            We want to solve this equation for  w  .  Subtract  2c  from both sides.

-2c + 80  =  -0.5w         Multiply both sides by  -2 .

4c - 160  =  w

w  =  4c - 160

d.  To graph it, we can say  y = w   and  x = c  .

y  =  4x - 160            To find the x-intercept, plug in  0  for  y  and solve for  x .

0  =  4x - 160

40  =  x                     The x-intercept is  40 .

When there are  0  incorrect, there must be 40 correct to get  80  total points.

y  =  4x - 160            To find the y-intercept, plug in  0  for  x  and solve for  y .

y  =  4(0) - 160

y  =  -160                  The y-intercept is  -160 .

When there are  0  correct, there must be  -160  incorrect to get  80  total points.

Realistically...that is impossible to do!!!

e.     Using the points we just found:     (40, 0)  and  (0, -160)

slope   =   [-160 - 0] / [0 - 40]   =   160/40   =   4

f.     w  =  4c - 16                          If  c = 43 ,  then

w   =   4(43) - 160   =   12

The student must answer  12  questions wrong to get  80  points on the test.

But  43 + 12  =  55 , and there are only  50  questions on the test.

The student cannot get 12 wrong and 43 correct because there aren't enough questions. It's impossible for the student to get exactly  80  points on the test if he gets  43  correct.

The most he can get correct is  42 , which means he must get  8  wrong....remember....this is in order to get exactly 80 points on the test...no more, no less!

Nov 17, 2017

#1
0

Answer it all if possible, you can do it in parts, like A [send] B [send] and so on...

Nov 15, 2017
#2
+5

For A, since a correct answer is worth 2, and an incorrect is worth -1/2, it is simple multiplication

30*2=60

-1/2*5= -2.5

Subtract 2.5 from 60

60-2.5=57.5

In total, that leaves 57.5 points.

For B, I would have to say it is not possible to determine the score based off correct answers, due to the fact that incorrect answers deduct points, and unanswered aren't worth anything.

Nov 15, 2017
edited by DerpofTheAbyss  Nov 15, 2017
edited by DerpofTheAbyss  Nov 15, 2017
#3
+1

Thanks

FunMath  Nov 15, 2017
#4
+1

I still need a-f though, thatnks for a and b!

FunMath  Nov 15, 2017
#5
+5

total number of points  =  ( 2 * number correct ) - ( 0.5 * number incorrect )

a.     score   =   ( 2 * 30 ) - ( 0.5 * 5 )   =   60 - 2.5   =   57.5

b.     No, you must know the number correct and the number incorrect to determine the score.

c.     We want to set the score equal to  80  and solve for the number incorrect.

Also...let's say  c = number correct  and  w = number incorrect

80  =  2c - 0.5w            We want to solve this equation for  w  .  Subtract  2c  from both sides.

-2c + 80  =  -0.5w         Multiply both sides by  -2 .

4c - 160  =  w

w  =  4c - 160

d.  To graph it, we can say  y = w   and  x = c  .

y  =  4x - 160            To find the x-intercept, plug in  0  for  y  and solve for  x .

0  =  4x - 160

40  =  x                     The x-intercept is  40 .

When there are  0  incorrect, there must be 40 correct to get  80  total points.

y  =  4x - 160            To find the y-intercept, plug in  0  for  x  and solve for  y .

y  =  4(0) - 160

y  =  -160                  The y-intercept is  -160 .

When there are  0  correct, there must be  -160  incorrect to get  80  total points.

Realistically...that is impossible to do!!!

e.     Using the points we just found:     (40, 0)  and  (0, -160)

slope   =   [-160 - 0] / [0 - 40]   =   160/40   =   4

f.     w  =  4c - 16                          If  c = 43 ,  then

w   =   4(43) - 160   =   12

The student must answer  12  questions wrong to get  80  points on the test.

But  43 + 12  =  55 , and there are only  50  questions on the test.

The student cannot get 12 wrong and 43 correct because there aren't enough questions. It's impossible for the student to get exactly  80  points on the test if he gets  43  correct.

The most he can get correct is  42 , which means he must get  8  wrong....remember....this is in order to get exactly 80 points on the test...no more, no less!

hectictar Nov 17, 2017
#6
+3

Thank you so so so much hectictar

FunMath  Nov 17, 2017