Question of the Day

Can you answer today's question?

Register Next Tests:
12/6 , 1/24

http://sat.collegeboard.org/practice/sat-question-of-the-day
Jul
15
Question of the Day Statistics
Number Answered
Correct 93,936
Incorrect 102,593
196,529 responses
47% correct
See Last Thirty Questions:

Mathematics > Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer. 

A 6-sided number cube, with faces numbered 1 through 6, is to be rolled twice. What is the probability that the number that comes up on the first roll will be less than the number that comes up on the second roll?

Answer Choices

Correct!

Explanation

The outcome space for this experiment is the set of all ordered pairs (a comma b) where a represents the first number that comes up, and b represents the second one. Since a and b can take all the values 1 through 6, there will be a total of 36 possible outcomes. The outcomes can be represented in a table as shown:

graphic

Among all the pairs (a comma b), 6 are pairs for which a = b. So 30 remaining pairs will have a not equal to b. Notice that the number of pairs  (a comma b) for which a less than b is the same with the number of pairs 

(a comma b) for which a greater than b. Therefore the number of pairs 

(a comma b) for which a less than b, is 15(half of 30). Then the probability that a less than b is equal to (number of pairs (a comma b) comma where a less than b) over (number of all possible outcomes) = 15 over 36 = 5 over 12.

Log in, track your progress and review questions.
Want to brush up on your skills? Just visit our Practice Questions area.

Buy Together, Get $10 Off

Buy Together & Get $10 Off
Study Guide
Online Course

The online course includes explanations and auto essay scoring for the Study Guide's 10 practice tests.

The Official Study Guide for All SAT Subject Tests™: 
Second Edition

Subject Test Study Guide

Get ready for test day with a brand new edition of our best-selling SAT Subject Test Study Guide! Brought to you by the test-maker, this is the ONLY study guide with actual, previously administered tests for all 20 SAT Subjects Tests™ to provide you with the real test-taking experience.

See Inside