Combinatorics
Math ⇒ Statistics and Probability
Combinatorics starts at 9 and continues till grade 12.
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See sample questions for grade 10
A password consists of 2 letters followed by 3 digits. How many different passwords can be formed if repetition is allowed?
How many different 3-digit numbers can be formed using the digits 1, 2, 3, 4, and 5, if no digit is repeated?
How many different 4-letter words (real or imaginary) can be formed from the letters A, B, C, D, and E if no letter is repeated?
How many different 5-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, and 7 if no digit is repeated?
How many different ways can the letters of the word 'MATH' be arranged?
A password consists of 2 letters followed by 3 digits. How many different passwords can be formed if repetition is allowed?
How many different 4-letter words (real or imaginary) can be formed from the letters A, B, C, D, and E if no letter is repeated?
How many different 5-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, and 7 if no digit is repeated?
How many ways can 3 identical balls be placed into 4 distinct boxes?
Which of the following is a permutation? (1) Choosing 3 students from a class (2) Arranging 3 books on a shelf (3) Selecting 3 fruits from a basket (4) Picking 3 cards from a deck
Which of the following is the correct formula for the number of combinations of n objects taken r at a time? (1) n!/(n-r)! (2) n!/(r!(n-r)!) (3) n^r (4) n!
Which of the following is the correct formula for the number of permutations of n objects taken r at a time? (1) n!/(n-r)! (2) n!/(r!(n-r)!) (3) n^r (4) n!
Which of the following statements is true? (1) Permutations are used when order matters. (2) Combinations are used when order matters. (3) Both are used when order does not matter. (4) Neither is used when order matters.
The number of ways to arrange n distinct objects in a line is called a ________.
The number of ways to arrange n objects in a circle is ________.
The number of ways to choose r objects from n objects when order does not matter is called a ________.
True or False: 0! (zero factorial) is equal to 1.
True or False: The number of combinations of n objects taken 1 at a time is n.
True or False: The number of permutations of n objects taken all at a time is n!.
True or False: The order matters in a combination.
