Question 202514
Since Rachel needs to get AT LEAST a 90-average on the four exams, using the average formula, which states: 


{{{(sum of scores)/(number of scores) = Average}}}, we then get the following inequality:  


{{{(75+95+97+x)/4>=90}}}


Multiplying each expression by the LCD, 4, we get:  {{{267 + x>=360}}}, or {{{x>=93}}}


Therefore, in order for Rachel to average at least a 90 on all four exams, she has to score a 93, or more on her 4th and final exam.


Check
{{{(75 + 95 + 97 + 93)/4 >= 90}}}


{{{360/4>=90}}}


{{{90>=90}}}