SAT question dae79de4 (Probability And Conditional Probability)

Question

The table summarizes customers who visited a car dealership in the last month by age and number of visits they made to the dealership. If a customer from the last month is selected at random, what is the probability that the selected customer is at least 40 years old?

College Board · Accepted Answer

The correct answer is D. Choice D is correct. Based on the table, there are a total of 135 customers who visited the car dealership in the last month, and 105 of these customers are at least 40 years old. If a customer from the last month is selected at random, the probability that the selected customer is at least 40 years old is equal to the number of customers who are at least 40 years old divided by the total number of customers. Therefore, the probability that the selected customer is at least 40 years old is (105)/(135) .

CookSAT · Answer

Note: The fraction 105/135 in the calculator gives the probability, matching the row total for “at least 40 years old” over the grand total.

	$1$ visit	$2$ or more visits	Total
Less than $40$ years old	$15$	$15$	$30$
At least $40$ years old	$20$	$85$	$105$
Total	$35$	$100$	$135$

Explanation

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Why the other choices are wrong

SAT Question dae79de4: Probability And Conditional Probability answer and explanation with Desmos solution

Explanation

Enter in Desmos:

Why the other choices are wrong