The problem asks you to determine what grade on the fifth test will give you a mean score of at least 85, given your scores on the first four tests.

The four test scores you have are:

• 79
• 85
• 86
• 88

Step 1: Calculate the sum of the first four test scores:

$79 + 85 + 86 + 88 = 338$

Step 2: Set up the equation for the mean score:

Let $x$ be the grade on the fifth test. To have a mean of at least 85, the sum of all five test scores must be at least $85 \times 5 = 425$.

So the equation becomes: $338 + x \geq 425$

Step 3: Solve for $x$:

$x \geq 425 - 338$ $x \geq 87$

Thus, you need to score at least 87 on your fifth test to achieve a mean score of 85 or more.

Would you like further details on the steps or have any other questions about this?

Related Questions:

1. How do you calculate the mean of a set of numbers?
2. What is the formula for determining the mean of multiple test scores?
3. How can you use inequalities in word problems like this one?
4. What other ways could you calculate required scores in a scenario like this?
5. How do you interpret the result of an inequality in a real-life context?

Tip: To quickly calculate the mean, always start by adding the numbers and dividing by the total number of items.