254 algebra De mystif ieD
✔SOLUTIONS
- Let x = the next grade.
93 89 96 98
5
95
376
5
95
5376
5
595
37
++++=
+ =
+
=
x
x
x ()
66 475
376 376
99
+=
−−
=
x
x
Crystal’s last grade needs to be 99 in order to raise her average to 95.
- Let x = the next grade.
79 82 77 81 78
6
80
397
6
80
6397
6
680
+++++ =
+ =
+
=
x
x
x ())
397 480
397 397
83
+=
−−
=
x
x
Nichelle’s next grade needs to be 83 to raise her average to 80.
- Let x represent the presentation grade. The test average is (61 + 63 + 65 +
83)/4 = 68. Then^34 test average +^14 presentation grade = 70 becomes
3
468
1
() + 4 x 70 =
.
3
4
68 1
4
70
51
4
70
51 51
4
19
419
76
()
()
+=
+=
−−
=
=
=
x
x
x
x
x
The student needs a 76 on his presentation to have a course grade of 70.