Brooke has scores of 84, 72, 90, 95, and 87 on her first five quizzes. after taking the sixth quiz, brooke’s mean score increased. which could be brooke’s sixth quiz score? check all that apply. 85 90 83 86 92 89

ANSWER



EXPLANATION

We first determine the mean of the first five quizzes,




Let sixth number be


Then the mean of the 6 scores should now be more than 85.6.

This implies that,



Thus,



We now solve for y to obtain,









Therefore Brooke's six score should be,

Remember, you can do anything to an equation as long as you do it to both sidesminus 36 from both sides4.5(8-x)=66-2.5(3x+24)distribute36-4.5x=66-7.5x-60add like terms36-4.5x=-7.5x+6add 7.5x to both sides36+3x=6minus 36 from both sides3x=-30divide both sides by 3x=-10