PSAT Math Multiple-Choice Question 517: Answer and Explanation

Question: 517

Distance from Sun (in millions of miles)	Number of planets
0–499	5
500–999	1
1,000–1,999	1
More than 2,000	2

The data table above shows the distribution of distance from the Sun for nine planets, including the dwarf planet Pluto, in Earth’s solar system. If an astronomer randomly selects one of these planets to investigate further, what is the probability that the planet’s distance from the Sun is greater than 999 million miles?

• A.
• B.
• C.
• D.

Correct Answer: B

Explanation:

B

The question asks for a probability, which is defined as . Read the table carefully to find the numbers to make each probability. The astronomer will select one of these planets, and there are 5 + 1 + 1 + 2, or 9, planets, so that is the # of possible outcomes. The question asks about planets greater than 999 million miles from the Sun. Of these planets, 1 is between 1,000 and 1,999 million miles away and 2 are more than 2,000 million miles away, so the # of outcomes you want is 3. The probability is , or . The correct answer is (B).