SAT Math Multiple Choice Question 871: Answer and Explanation
|Tropical Storms||Hurricanes||Major Hurricanes (Cat. 3+)||Total|
1. The students in an environmental science class will be randomly assigned a storm toresearch, with no two students researching the same storm. Given that the studentswill each be assigned a hurricane or a major hurricane for their reports, what isthe probability that a student will be assigned a storm that occurred prior to 2000?
- A. 0.2618
- B. 0.3574
- C. 0.6426
- D. 0.7324
Correct Answer: B
Category: Problem Solving and Data Analysis / Statistics and Probability
Strategic Advice: In a probability question, the phrase "given that" indicates conditional probability, which means the total possible outcomes will be different from the total number of values in the table. Take this into account when setting up your calculations.
Getting to the Answer: You're told that all students will be assigned a hurricane or major hurricane, so the total possible outcomes is the sum of these categories: 175 + 74 = 249. The question asks for the probability that a randomly selected storm occurred prior to 2000, so add together the number of hurricanes and major hurricanes that occurred before 2000 (which includes 1990-1994 and 1995-1999): 23 + 5 + 41+ 20 = 89. This means the probability you're after is. (B) is therefore correct.