document.write( "Question 1182133: Hello, I just need someone to confirm my answers for these questions (if I'm wrong someone please help and correct me thank you:\r
\n" ); document.write( "\n" ); document.write( "In one section of a math test paper, a student answers 3 out of 4 questions in that section. In How many ways can this section be answered if different orders in which the questions are answered count as different ways.\r
\n" ); document.write( "\n" ); document.write( "My answer is 4*3*2 = 24\r
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\n" ); document.write( "\n" ); document.write( "In how many ways can 4 boys and 2 girls seat themselves in a row if
\n" ); document.write( "(a) the 2 girls are to seat next to each other
\n" ); document.write( "(b) the 2 girls are not to seat to each other
\n" ); document.write( "(c) the 2 girls are to be separated by 2 boys between them \r
\n" ); document.write( "\n" ); document.write( "for (a) I did 4!*2!*6 ( 4! is for the boys, 2! for the girls and 6 positions the girls can start at). This for me is a bit tricky for some reason.\r
\n" ); document.write( "\n" ); document.write( "for (b) I did 6! - 2!(6-2+1)! = 480\r
\n" ); document.write( "\n" ); document.write( "for (c) I did 4! * 2! * 3 (4! from the boys. 2! from the girls and 3 from the fact that there are only 3 cases of this that can be happened)\r
\n" ); document.write( "\n" ); document.write( "in how many ways can 5-digit numbers be formed using the digits 0,1,3,4,5 if
\n" ); document.write( "(e) no repetition of digits is allowed
\n" ); document.write( "(d) repetition of digits is allowed\r
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\n" ); document.write( "\n" ); document.write( "for (e) I did 4*4*3*2*1 = 96 (4 at first because zero is not allowed in the first digit of a number)\r
\n" ); document.write( "\n" ); document.write( "for (d) i did 5*5*5*5*5\r
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Algebra.Com's Answer #812121 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "In one section of a math test paper, a student answers 3 out of 4 questions in that section. In How many ways can this section be answered if different orders in which the questions are answered count as different ways.
\n" ); document.write( "My answer is 4*3*2 = 24

\n" ); document.write( "Correct

\n" ); document.write( "In how many ways can 4 boys and 2 girls seat themselves in a row if

\n" ); document.write( "(a) the 2 girls are to seat next to each other
\n" ); document.write( "I did 4!*2!*6 ( 4! is for the boys, 2! for the girls and 6 positions the girls can start at). This for me is a bit tricky for some reason.

\n" ); document.write( "Not quite. There are only 5 places the girls can start at. So 4!*2!*5 = 240.

\n" ); document.write( "Alternatively....
\n" ); document.write( "Treat the 2 girls as one unit; there are then 5 things to be arranged, and there are 2 different arrangements in one of those things: (5!)(2)=240. Same answer by a different method.

\n" ); document.write( "(b) the 2 girls are not to seat to each other
\n" ); document.write( "I did 6! - 2!(6-2+1)! = 480

\n" ); document.write( "Correct.

\n" ); document.write( "(c) the 2 girls are to be separated by 2 boys between them
\n" ); document.write( "I did 4! * 2! * 3 (4! from the boys. 2! from the girls and 3 from the fact that there are only 3 cases of this that can be happened)

\n" ); document.write( "Correct.

\n" ); document.write( "In how many ways can 5-digit numbers be formed using the digits 0,1,3,4,5 if
\n" ); document.write( "(e) no repetition of digits is allowed
\n" ); document.write( "I did 4*4*3*2*1 = 96 (4 at first because zero is not allowed in the first digit of a number)

\n" ); document.write( "Correct.

\n" ); document.write( "(d) repetition of digits is allowed
\n" ); document.write( "I did 5*5*5*5*5

\n" ); document.write( "Not quite; I think you know why. (Look at your answer for (e))

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