Final answer:
Paul needs to bake 5 brownies to reach his goal of earning $10 by selling four out of every five brownies at $2.50 each.
Step-by-step explanation:
Paul expects to sell four out of every five brownies he bakes to earn $10. To determine how many brownies he needs to bake, let's assume the price of one brownie is x dollars. Then, selling four brownies will earn him 4x dollars. Since his goal is to earn $10, we need to solve the equation 4x = $10.
Dividing both sides by 4, we get x = $10 / 4, which simplifies to x = $2.50. Hence, each brownie is sold for $2.50. If Paul sells four out of five brownies he bakes, for each batch of five, only four are sold. To reach the $10 target, he will indeed need to have five brownies, but only sell four.
Therefore, Paul needs to bake 5 brownies to expect a sale of 4 brownies at $2.50 each to reach his $10 goal.