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anonymous

  • one year ago

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

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  1. anonymous
    • one year ago
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    B

  2. anonymous
    • one year ago
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    the answer is 87

  3. NotTim
    • one year ago
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    Should give an explanation; I actually wanna know how to do this.

  4. anonymous
    • one year ago
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    sure

  5. anonymous
    • one year ago
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    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 \[255-171<171+n-171 \le 270-171\] \[84<n \le 99\]

  6. anonymous
    • one year ago
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    Correction: "the average must be between 80 and 90 inclusive"

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