Re: Camille's average on her 6 math tests this marking period is
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22 Sep 2017, 06:05
Since the mean of 6 grades is 75, the sum of this grade is equal to 6*75 = 450. Then, we can check the answers by subtracting them from 450 and dividing by 5, the number of remaining grades. Since the answers are in increasing order we should start by answer C to have an idea of the direction in which we should move.
Using C, we would get (450-30)/5 = 84, too low. This means that we are subtracting a too high grade. Then, we should move up. Let's try with B.
Using B, we obtain (450-25)/5 = 85. Here we are. Answer B is the right one!