document.write( "Question 1131556: The average for Aaron’s test scores must be at least a 90 to earn an a in the class Aaron scored an 87 on the first test and 91 on the second test what scores can Aaron earn on the third test to guarantee at least an a in the class \n" ); document.write( "

Algebra.Com's Answer #748237 by greenestamps(13216) $\"\"$ $\"About$

You can put this solution on YOUR website!

\n" ); document.write( "His two test scores so far are 87 and 91, a total of 178.

\n" ); document.write( "To get an average of 90 or more on three tests, the sum of the three test scores must be 270 or more.
270-178 = 92; he needs at least a 92 on the third test to average 90 or more and get an A.

\n" ); document.write( "Here is a faster and easier way to answer a question like this involving an average of numbers that are all close together: compare each number to the desired average to see where the total lies compared to the average.

\n" ); document.write( "In this problem, the desired average is 90. The first score was 87, which is -3 compared to the average; the second score was 91, which is +1 compared to the average. So the first two tests combined are -2 compare to the average.

\n" ); document.write( "That means the third score, in order to attain the desired average, must be +2 (at least) compared to the average: 90+2 = 92. \n" ); document.write( "

\n" );