document.write( "Question 88730: A test has 10 true/false questions. How many different tests can be turned in to the teacher? \n" ); document.write( "
Algebra.Com's Answer #64494 by bucky(2189)![]() ![]() ![]() You can put this solution on YOUR website! The first question could be answered either true or false. \n" ); document.write( ". \n" ); document.write( "If you answered true on the first question, you could answer either true or false on the \n" ); document.write( "second question. \n" ); document.write( ". \n" ); document.write( "If you answered false on the first question you could answer either true or false on the \n" ); document.write( "second question. \n" ); document.write( ". \n" ); document.write( "So after two questions you have four possible situations: \n" ); document.write( ". \n" ); document.write( "True & then True \n" ); document.write( "True & then False \n" ); document.write( "False & then True \n" ); document.write( "False & then False \n" ); document.write( ". \n" ); document.write( "Now for each of those 4 possibilities, you could answer either true or false on the third question. \n" ); document.write( "So after 3 questions you would have 8 possible test answers ... 4 * 2. \n" ); document.write( ". \n" ); document.write( "And for each of the 8 possible answer situations on the third question, you can answer either \n" ); document.write( "true or false on the fourth question. This will give you 8 * 2 = 16 possible answers after \n" ); document.write( "the fourth question. \n" ); document.write( ". \n" ); document.write( "By now you have probably noticed the pattern. Each additional question increases the number \n" ); document.write( "of possible answer configurations by a factor of 2. \n" ); document.write( ". \n" ); document.write( "This pattern is reflected by the equation: \n" ); document.write( ". \n" ); document.write( "Number of different tests = 2^n \n" ); document.write( ". \n" ); document.write( "where n represents the number of questions on the test. \n" ); document.write( ". \n" ); document.write( "If there were just 1 question on the test there would be 2^1 possible answers (either true \n" ); document.write( "or false). If there were 2 questions on the test, the number of possible answer combinations \n" ); document.write( "would be 2^2 or 4. Similarly for 3 questions there would be 2^3 = 8 possible combinations. \n" ); document.write( ". \n" ); document.write( "Extending on this pattern, for a 10 question test there would be 2^10 possible combinations \n" ); document.write( "of answers. And 2^10 = 1024 possible answer combinations. That means that the teacher \n" ); document.write( "could possibly receive 1024 tests that are all different by at least one answer. \n" ); document.write( ". \n" ); document.write( "Hope this provides you with a way of figuring out a process for solving questions \n" ); document.write( "such as this one. \n" ); document.write( " |