SAT question b6569d0e (Probability And Conditional Probability)

Question

The table above gives the number of United States presidents from 1789 to 2015 whose age at the time they first took office is within the interval listed. Of those presidents who were at least 50 years old when they first took office, what fraction were at least 60 years old?

College Board · Accepted Answer

The correct answer is B. Choice B is correct. The sample space is restricted to the presidents who were at least 50 years old when they first took office. Therefore, the sum of the values in the final four rows of the table, 13 + 11 + 7 + 3 = 34 , is the total number of presidents in the sample space. The number of presidents who were at least 60 years old is the sum of the values in the final two rows of the table: 7 + 3 = 10 . Thus, the fraction of the 34 presidents who were at least 50 years old when they first took office who were at least 60 years old is (10)/(34) .

CookSAT · Answer

Note: Count the 10 presidents at least 60, then divide by all 34 presidents who were at least 50.

United States Presidents from 1789 to 2015
Ages	Number
$40$ – $44$	$2$
$45$ – $49$	$7$
$50$ – $54$	$13$
$55$ – $59$	$11$
$60$ – $64$	$7$
$65$ – $69$	$3$

Explanation

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Why the other choices are wrong

SAT Question b6569d0e: Probability And Conditional Probability answer and explanation with Desmos solution

Explanation

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Why the other choices are wrong