# What am I doing wrong here?

• Aug 9th 2009, 08:13 AM
bobbyboy1111
What am I doing wrong here?
I know it must be a small mistake and it is driving me mad!(Crying) This is a question with a follow up, so be sure to read the whole thing first.

1. Mr. Boberts gives a test, and his students’ scores range from 30 to 70. He decides to curve the scores, so that they range from 65 to 95. Let “x” be an original score, and “y” be a curved score. Using the ordered pairs (30,65) and (70,95), write the equation in slope/intercept form that he should use to curve the test scores.

m = (65) - (95)/(30) - (70)
m = -30/-40
m = - (-30/40)
m = - (-3/4)
m = 3/4

y = mx + b
65 = (3/4)(30) + b
65 = 90/4 + b
65 = 45/2 + b
65 + 45/2 = b
130/2 + 45/2
175/2 = b

So... y = (3/4)x + 175/2

Following up: In the scenario above, what will an original score of 62 become?

y = (3/4)62 + 175/2
y = 93/2 + 175/2
y = 268/2
y = 134

-Thanks will be given to those who help-(Wait)
• Aug 9th 2009, 08:27 AM
skeeter
Quote:

Originally Posted by bobbyboy1111
I know it must be a small mistake and it is driving me mad!(Crying) This is a question with a follow up, so be sure to read the whole thing first.

1. Mr. Boberts gives a test, and his students’ scores range from 30 to 70. He decides to curve the scores, so that they range from 65 to 95. Let “x” be an original score, and “y” be a curved score. Using the ordered pairs (30,65) and (70,95), write the equation in slope/intercept form that he should use to curve the test scores.

m = (65) - (95)/(30) - (70)
m = -30/-40
m = - (-30/40)
m = - (-3/4)
m = 3/4

y = mx + b
65 = (3/4)(30) + b
65 = 90/4 + b
65 = 45/2 + b
65 + 45/2 = b ... should be 65 - 45/2 = b

...
• Aug 9th 2009, 09:17 AM
bobbyboy1111
O.k., I've made my corrections. Is this correct?

m = (65) - (95)/(30) - (70)
m = -30/-40
m = - (-30/40)
m = - (-3/4)
m = 3/4

y = mx + b
65 = (3/4)(30) + b
65 = 90/4 + b
65 = 45/2 + b
65 - 45/2 = b
130/2 - 45/2
85/2 = b

So... y = (3/4)x + 85/2

Follow up: In the scenario above, what will an original score of 62 become?

y = (3/4)62 + 85/2
y = 93/2 + 85/2
y = 178/2
y = 89