Average Score

[harpazo]

Timothy's average score on the first 4 tests was 76. On the next 5 tests his average score was 85. What was his average score on all 9 tests?

Sum of terms = average • number of terms.

Let S = sum of terms

S = 76(4)

S = 304

Next Test:

Let S_1 = sum of terms

S_1 = 85(5)

S_1 = 425

Let A = average for all 9 tests.

A = (S + S_1)/9

A = (304 + 425)/9

A = 729/9

A = 81

Is this right?

 

[Otis]

... Let A = average [score] for all 9 tests ...

That's a good definition; you've specified what you're averaging.

Let S = sum of terms
Let S_1 = sum of terms

According to those definitions, S = S_1.

They could each be improved, by specifying what you're summing.

Let S = sum of first 4 (averaged) test scores

Let S_1 = sum of next 5 (averaged) test scores

A = 81

Is this right?

Yes.

?

 

[harpazo]

That's a good definition; you've specified what you're averaging.



According to those definitions, S = S_1.

They could each be improved, by specifying what you're summing.

Let S = sum of first 4 (averaged) test scores

Let S_1 = sum of next 5 (averaged) test scores

S = first test scores

S_1 = next 5 test scores

Yes.

?

 

[harpazo]

That's a good definition; you've specified what you're averaging.



According to those definitions, S = S_1.

They could each be improved, by specifying what you're summing.

Let S = sum of first 4 (averaged) test scores

Let S_1 = sum of next 5 (averaged) test scores



Yes.

?

S = first test scores

S_1 = next test scores

 

[Otis]

S = first test scores

S_1 = next test scores

Those are still sum-what vague, heh. That is, each definition ought to (at least) contain the phrase 'sum of'.

 

[MarkFL]

S = first test scores

S_1 = next test scores

I would use a subscript on both, for consistency.

 

[Otis]

I would use a subscript on both, for consistency.

My thought, too (S₁ and S₂), but I chose not to add that suggestion because I had concerns that it would upset harpazo.

?

 

[harpazo]

Thanks everyone.