Question

After six biology tests, Ruben has a mean score of 77. What score does Ruben need on the next test to raise his average (mean) to 79?

Answer 1

Let 'x' denote the score Ruben need to score on the next, i.e. seventh test so that his average raises to 79.

Now, we are given that, Ruben has a mean score of 77 on first six tests. Now, we find the total score on the first 6 tests. We observe the following formula:

Now, the total score on the seven tests (including the first six and the seventh test with score 'x') = 462 + x

Now, we need that the mean score on the seven tests is 79. Now, again we use the formula for mean:

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