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Answer: Surface area is the sum of the areas of all faces (or surfaces) on a 3D shape. A cuboid has 6 rectangular faces. To find the surface area of a cuboid, add the areas of all 6 faces. We can also label the length (l), width (w), and height (h) of the prism and use the formula, SA=2lw+2lh+2hw, to find the surface area
Hi! It will be a pleasure to help you finding the solution to this problem, so let's solve each part:
<h2>PART 1.</h2><h3>Finding the correct expression.</h3><h3>Correct answer:</h3>

From the problem, we know the following data of the problem:
- Laval parked at the beach.
- Laval paid a fixed price of $4 for a pass.
- Laval paid $1.50 for each hour.
Our goal is to find the the expression for the total cost for parking at the beach for h hours. So:
Step 1: Since we have a fixed price, this value will appear in our expression:

Step 2: Since Laval paid $1.50 for each hour, this can be represented as the following expression:

Finally, we can write total cost (C) as the sum of these two expressions:

Finally, our correct option is A:

<h2>PART 2.</h2><h3>Finding h.</h3><h3>Correct answer:</h3>
5 hours
Here we have to find how many hours Laval spent at the beach knowing that he paid a total amount of $11.50. From the previous part, we know that our expression is:

Finally, he spent 5 hours at the beach
We are looking for the probability :

Transform the law to standard normal like this:

The above formula is equivalent to this one:

From normal law table, we read the value of

.

Solving the above equation for the score n:


, it is the score we are looking for.