Math Problem Statement

a student needs an average of at least 70% on 5 exams. after taking 4 exams, the scores are 65,72,68, and 75. write and solve an inequality to find what score the student must get on the fifth exam to pass

Solution

To find the minimum score the student needs on the fifth exam to have an average of at least 70%, we can set up an inequality.

Let the score on the fifth exam be represented by xx.

  1. The average of the five exams must be at least 70%, so we have:

    65+72+68+75+x570\frac{65 + 72 + 68 + 75 + x}{5} \geq 70

  2. Simplify by multiplying both sides by 5:

    65+72+68+75+x35065 + 72 + 68 + 75 + x \geq 350

  3. Add up the scores from the first four exams:

    280+x350280 + x \geq 350

  4. Subtract 280 from both sides:

    x70x \geq 70

So, the student must score at least 70 on the fifth exam to achieve an average of 70% or more.

Would you like more details on solving inequalities, or have any questions?

Here are five related questions for further exploration:

  1. What if the student wanted an average of 75% instead of 70%?
  2. How would the result change if the scores were slightly higher or lower?
  3. What is the highest average the student could achieve with a fifth score of 100%?
  4. How do we calculate weighted averages if one test is worth more?
  5. How would the inequality look if the average requirement was less than 70%?

Tip: When solving inequalities, remember to reverse the inequality sign if you multiply or divide by a negative number.

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Math Problem Analysis

Mathematical Concepts

Algebra
Inequalities
Averages

Formulas

Average formula: (sum of values) / number of values
Inequality properties

Theorems

Solving inequalities
Properties of averages

Suitable Grade Level

Grades 7-9