Chapter 8 linear appliCaTionS 255
- Let x represent Ava’s final exam grade. Her test average is (68 + 73 + 80
- 95)/4 = 79. Then^13 test average + 31 presentation grade + 31 final exam
grade is 80 becomes
- 95)/4 = 79. Then^13 test average + 31 presentation grade + 31 final exam
1
3
79 1
3
75 1
3
80
79
3
25
3
80
379
3
25
3
()++() ()=.
++=
++
x
x
x
=
++⋅=
++=
380
379
3
3253
3
240
79 75 240
()
() x
x
1154 240
154 154
86
+=
−−
=
x
x
Ava’s final exam grade needs to be 86 to obtain an average of 80.
- Let x = sixth quiz grade. The course grade^45 quiz grade +^15 book report
becomes
4
5
72 66 69 80 85
6
1
5
+++++ 90
x + ().
Simplified, the above is
4
5
372
6
18 4372 4
30
18 1488 4
30
+ 18
xx+=()+ += + x+.
We want this quantity to equal 80.
1488 4
30
18 80
301488 4
30
18 30 80
30148
+ +=
+ +
=
x
x ()
884
30
+ 30 18 2400
x +=()