How do you solve... Susan Jacobson has grades of 76 and 81 on her first to algebra tests. If she wants an average of at least 80 after her third test, what score must she make on her test?

Question

ash2326 · Answer

@melb94 Do you know how to find average of three no.s?

anonymous · Answer

no i do not

ash2326 · Answer

Do you understand what average implies?

ash2326 · Answer

@melb94

anonymous · Answer

average would be the sum of all the test?

ash2326 · Answer

Sum of all the test marks is the Sum,
Suppose you take a series of exams and you score different in each of the exam, suppose we want to know how well you performed, we would know that from the average.
Suppose you scored 90, 95, 100, 80, 85
Do you follow this?

anonymous · Answer

I think so.

ash2326 · Answer

To find average we'll find the sum of all the test scores
S=90+95+100+80+85
Can you find the sum?

anonymous · Answer

450

ash2326 · Answer

Good and how many exam did you take?

anonymous · Answer

5

ash2326 · Answer

Good then you average score would be
$$A=\frac{S}{5}=\frac{450}{5}=$$
Can you find this?

anonymous · Answer

90?

ash2326 · Answer

yes, that's how average is calculated. Did you follow?

anonymous · Answer

yes

ash2326 · Answer

ok, let's work on your problem. Can you try?

anonymous · Answer

So the equation would be?$$76+81+x \ge80$$

ash2326 · Answer

yes, that's how average is calculated. Did you follow?

ash2326 · Answer

We will use equal to symbol and you have to make use of the no. of tests

anonymous · Answer

so 76+81+80/3?

ash2326 · Answer

but we don't know the score of the third test, let it be x

anonymous · Answer

so 76+81+x=157+x
and then divide by 3?

ash2326 · Answer

yes, and we already have the average in the question

anonymous · Answer

so the answer would be 83?

ash2326 · Answer

yes, good work.

anonymous · Answer

yay! thanks

ash2326 · Answer

Welcome :D