Lets say the student takes the maximum socre on his last test, so he gets 100. Now, his average on the six texts will be:
(75+85+90+95+94+100)/6 = 89.83
So, if taking 100 is not enough to get to the average of 90, this means he would need a score greater than 100, which is impossible as 100 is the maximum. So, the student CAN'T get an A
