URGENTTT
A student scored 84 and 87 on her first two quizzes. Write and solve a compound inequality to find the possible values for a third quiz score that would give her an average between 85 and 90, inclusive.
-0.5

Question

URGENTTT 	
A student scored 84 and 87 on her first two quizzes. Write and solve a compound inequality to find the possible values for a third quiz score that would give her an average between 85 and 90, inclusive.
	-0.5<n<4.5
        84<n<99
        99<n<84
        80<n<98

anonymous · Answer

B

anonymous · Answer

the answer  is 87

nottim · Answer

Should give an explanation; I actually wanna know how to do this.

anonymous · Answer

sure

anonymous · Answer

The student already scored 84 and 87, so the average between the scores would be 
$$\frac{ 84 + 87 + n }{ 3 }$$
and n is the third quiz score, so, the average must be between -0.5 and 4.5 inclusive 
The "inclusive" means less or equal than
So
$$85<\frac{ 84 + 87 + n }{ 3 }\le90$$
If you multiply the entire inequality by 3 you get
$$255<84+87+n \le 270$$
and now you can sum up the 84+87 which is 171
now, you substract 171 to the entire inequality to leave x alove so 
$$255-171<171+n-171 \le 270-171$$
$$84<n \le 99$$

anonymous · Answer

Correction: "the average must be between 80 and 90 inclusive"