Question

Mike has these marks on his report card ; english =82% , french=75% , history =78% , science=80% what mark will he need in math if he wants to earn a mean mark of 80% across all these subjects ?is it possible for him to earn a mean mark of 85%

need help

Answer 1

80%

No

Explanation:

The mean of a data set is the average value.

How to Find Mean

The mean of a data set is the sum of all the values divided by the number of terms. For example, take the set {1, 3, 4, 7, 9, 12}. First, add all the values together: 1+3+4+7+9+12 = 36. Then divide by the number of terms, 6: 36/6 = 6. The mean is 6.

Minimum Score

To find the minimum score needed, we need to work backward from the mean. We want a mean of 80, and we have 5 terms. So, multiply 80 * 5 to find the sum of the scores.

• 80 * 5 = 400

This means when all 5 scores are added together, they must equal 400. Now, we can subtract the scores of the 4 known classes. This will give us the score for math.

• 400 - (82 + 75 + 78 + 80) = 85

This means that Mike needs an 85% in math to reach a mean of 80. Any lower and the mean will be less than 80%.

Mean of 85%

The last question asks if a mean of 85% is possible. To answer this we can solve the same way above but with a desired mean of 85%. Start by multiplying by the number of terms.

• 85 * 5 = 425

Then, subtract the known values.

• 425 - (82 + 75 + 78 + 80) = 110

Assuming there is no extra credit, a score of 110 is not possible. So, Mike cannot reach a mean of 85%.