Friday

August 22, 2014

August 22, 2014

Posted by **michele** on Thursday, April 14, 2011 at 10:52am.

I think this a permutation question need help

- counting -
**MathMate**, Thursday, April 14, 2011 at 11:26amThis is a combination question, since the order in which the questions are answered is not important.

All students have to answer 4 questions out of 5, which means that students can skip exactly one question, any single question.

So there are two cases:

Either

1. the student answers 1 question out of the first 2, and 3 questions out the the last 3,

or

2. the student answers 2 questions out of the first 2 and 2 questions out of the last 3.

Case 1:

There are 3 choices in question 1*or*2, 4 choices each in the remaining 3 questions, so the number of answers for the particular choice of questions is 3*4*4*4=192.

The number of choices of questions is

(2,1)=2 for the first group, and (3,3)=1

for a total of 2*1=2 choices of questions for case 1.

The total number of answers for case can be found by multiplying the number of choice of questions with the number of possible answers for each selection of questions = 2*192=384.

Case 2:

Number of possible answers for each selected combination of questions

= 3*3*4*4 = 144

Number of possible choice of questions:

(2,2)*(3,2)=1*3=3

Total number of possible answers for case 2 = 144*3=432

Total possible answers = 384+432 = 816

**Related Questions**

3rd grade math - on one test, chi answered 76 out of 100 questions correctly. on...

Math - On one test, Chi answered 76 out of 100 questions correctly . On another ...

Statistics - How do I figure out the answer to this ? It's been a while since I ...

math - A history teacher gives a 22 question T-F exam. In how many different ...

MATH - A history teacher gives a 27 question T-F exam. In how many different ...

ALGEBRA - A history teacher gives a 20 question T-F exam. In how many different ...

math - Sally answered 90% of the math test questions and 80% of the history test...

Mathematics - Maria answered all the problems on her math test. She answered 80 ...

Algebra - Bob received 6 points for each question he answered correctly on Part ...

geometry - in a trivia question ;your team answered 32 out of 40 question ...