Question 273051
williamson counts his midterm as 2/3 of the grade and his final as 1/3 of the grade.
wendy scored only 48on the midterm. 
What range of scores on the final exam would put wendy's average b/w 70 and 79 inclusive?
:
let x = grade required for a 70
Count the midterm grade twice and the final once, so you have
{{{(48 + 48 + x)/3}}} = 70
Multiply both side by 3
96 + x = 3(70)
x = 210 - 96
x = 114, so it's hopeless, cannot make a grade of 70
:
Compare to previous exercise which is: (Professor Williams give only a midterm exam and a final exam. 
The semester average is computed by taking 1/3 of the midterm exam score plus 2/3 of the final exam score. 
To get a C Stacey must have a semester average between 70-79 inclusive.
 If Stacey scored only 48 on the midterm, then for what range of scores on the final exam will Stacey get a c)
:
Count the midterm once and the final twice in this case
{{{(48 + 2x)/3}}} = 70
Multiply both side by 3
48 + 2x = 3(70)
2x = 210 - 48
2x = 162
x = {{{162/2}}}
x = 81, to get a 70 
and
{{{(48 + 2x)/3}}} = 79
Multiply both side by 3
48 + 2x = 3(79)
2x = 237 - 48
2x = 189
x = {{{189/2}}}
x = 94.5, to get a 79
:
Grade must be between 81 and 94.5 to have a C