Question 1144972
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None of the answer choices is right for the problem as written.<br>
"3 times more boys than girls" --> if the number of girls is x, then the number of boys is 3 times MORE THAN that, which is x+3x = 4x.<br>
Then the class average is<br>
{{{(x(86)+4x(90))/(5x) = 89.2}}}<br>
Unfortunately, in everyday sloppy English, "3 times more than x" and "3 times as much as x" are used to mean the same thing.  But they are different.  3 times as much as x is simply 3x; 3 times MORE THAN x is x, plus x 3 more times: x+3x = 4x.<br>
Apparently the intended wording of the problem is that there are 3 times AS MANY boys as girls.  That makes the number of boys 3x if the number of girls is x.  Then the class average is<br>
{{{(x(86)+3x(90))/(4x) = 89}}} --> answer D