SOLUTION: (1) How many ways can 20 objects be arranged into groups of 5? (order does not matter) (2) A test has five true-false questions that a student does not know how to answer. What is

Algebra ->  Probability-and-statistics -> SOLUTION: (1) How many ways can 20 objects be arranged into groups of 5? (order does not matter) (2) A test has five true-false questions that a student does not know how to answer. What is      Log On


   

Question 1048905: (1) How many ways can 20 objects be arranged into groups of 5? (order does not matter)
(2) A test has five true-false questions that a student does not know how to answer. What is the probability that student will get all five questions to correct?
(3) How many ways are there to arrange 5 people in 3 seats?
Answer by ikleyn(52799) About Me  (Show Source):
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(1) How many ways can 20 objects be arranged into groups of 5? (order does not matter)
(2) A test has five true-false questions that a student does not know how to answer. What is the probability that student will get all five questions to correct?
(3) How many ways are there to arrange 5 people in 3 seats?
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(1) C%5B20%5D%5E5 = 20%21%2F%2815%21%2A5%21%29 = %2820%2A19%2A18%2A17%2A16%29%2F%281%2A2%2A3%2A4%2A5%29 = 15504 ways.

   The number of combinations of 20 objects taken 5 at a time.

   See the lessons 
       - Introduction to Combinations

       - PROOF of the formula on the number of Combinations

       - Problems on Combinations
   in this site.


(2)  1%2F2%5E5 = 1%2F32.



(3)  5*4*3 = 60 ways.