Tim wants his mean (average) quiz score in history class to be 90. His first 3 quiz scores were 86, 92, and 94. What score should he make on the 4th quiz in order to have a mean (average) quiz score of exactly 90?

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x1 + x2 + x3 = 86 + 92 + 94 = 272

( x1 + x2 + x3 + x4 ) / 4 = 90

( 272 + x4 ) / 4 = 90 Multiply both sides by 4

272 + x4 = 90 * 4

272 + x4 = 360

x4 = 360 - 272 = 88

Tim wants his mean (average) quiz score in history class to be 90. His first 3 quiz scores were 86, 92, and 94. What score should he make on the 4th quiz in order to have a mean (average) quiz score of exactly 90?

is mean (average) quiz score in history class to be 90. His first 3 quiz scores were 86, 92, and 94. What score should he make on the 4th quiz in order to have a mean (average) quiz score of exactly 90?

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Well, Tim's goal is to have an average score of 90 after taking four quizzes. So far, his scores are 86, 92, and 94. We can use a little math humor to figure out the final score Tim needs to achieve his goal.

Let's call the score Tim needs on the fourth quiz "x." To find the average, we add up all the quiz scores and divide by the number of quizzes. In this case, it's (86 + 92 + 94 + x) / 4 = 90.

Now, let's get rid of that annoying fraction by multiplying both sides of the equation by 4: 86 + 92 + 94 + x = 360.

To find x, we subtract the sum of the first three scores from 360: x = 360 - (86 + 92 + 94).

Let's do a little addition: x = 360 - 272.

The final step: x = 88.

So, Tim needs to score an 88 on his fourth quiz to achieve an average quiz score of exactly 90. Good luck to Tim on his quest for that average!

To find the score Tim should make on the 4th quiz to have an average of exactly 90, we need to determine the total score he should have after all 4 quizzes.

Let's break down the problem step by step.

Step 1: Find the total score Tim has after the first three quizzes.
Since Tim's first three quiz scores were 86, 92, and 94, we can add them together to find the total score:
86 + 92 + 94 = 272

Step 2: Determine the total score Tim should have after all 4 quizzes.
Since Tim wants to have an average of exactly 90, we need to multiply this average by the total number of quizzes to find the total score:
Average score x Number of quizzes = Total score
90 x 4 = 360

Step 3: Find the score Tim should make on the 4th quiz.
To find the score Tim should make on the 4th quiz, we need to subtract the total score he already has from the desired total score for all 4 quizzes:
Target total score - Current total score = Score needed on the 4th quiz
360 - 272 = 88

Therefore, Tim should make a score of 88 on the 4th quiz in order to have an average quiz score of exactly 90.