Choose 3 digits, without repetition, from 1, 2, 4, 6, 8 to form 3-digit even numbers. How many numbers are there ?
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Choose 3 digits from 8, 6, 0, 5, 2 and 1 to form 3-digit numbers. How many odd numbers
are there? (The repetition of digits is not allowed)giúp me với
Exercise 7. Choose 2 numbers, without repetition, from 0, 3, 5, 6, 9 to form a 2-digit number. How many numbers with a digit “9” are there?
A. 6 B. 9 C. 7 D. 8
Choose 3 digits, without repetition, from 2, 3, 4, 5, 6 to form 3 – digit numbers. How many odd numbers (s) is/are there?
The Partial Permutations of N items taken K at a time is:
N! / (N - K)!
For N = 9 and K = 3, we get
9! / 6! = 7*8*9 = 504 possible three digit numbers.
Of those, odd are those which end in 1,3,5,7,9 (5 accepted endings) from a total of 1,2,3,4,5,6,7,8,9 (9 possible endings).
So, we take 5/9 of 504.
(5/9)*504 = 280.
Combinatorics21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?Different way: Cách khác nhau.22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. H...
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Combinatorics
21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?
Different way: Cách khác nhau.
22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?
At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.
23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. How many even number(s) greater than 300 is / are there? (The repetition of digits is not allowed)
Digit: Chữ số; 3-digit number: Số có 3 chữ số; Even number: Số chẵn; Greater than: Lớn hơn; Repetition of digits is not allowed: Các chữ số không được lặp lại.
24. A flight of stairs has 10 steps. Peter can go up for 1 step, 2 steps or 3 steps each time. How many way(s) is / are there for Peter to go up the stairs?
Step: Bước; Way: Cách.
25. Numbers are drawn from 80 integers 20 to 99. At least how many number(s) is / are drawn at random to ensure that there are two numbers whose sum is 85?
Integer: Số nguyên; At least: Ít nhất; Random: Ngẫu nhiên; Ensure: Chắc chắn; Sum: Tổng.
~ End of Paper ~
là seo pạn?mik hem hỉu??????????????????????
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Combinatorics
21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?
Different way: Cách khác nhau.
22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?
At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.
23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. How many even number(s) greater than 300 is / are there? (The repetition of digits is not allowed)
Digit: Chữ số; 3-digit number: Số có 3 chữ số; Even number: Số chẵn; Greater than: Lớn hơn; Repetition of digits is not allowed: Các chữ số không được lặp lại.
24. A flight of stairs has 10 steps. Peter can go up for 1 step, 2 steps or 3 steps each time. How many way(s) is / are there for Peter to go up the stairs?
Step: Bước; Way: Cách.
25. Numbers are drawn from 80 integers 20 to 99. At least how many number(s) is / are drawn at random to ensure that there are two numbers whose sum is 85?
Integer: Số nguyên; At least: Ít nhất; Random: Ngẫu nhiên; Ensure: Chắc chắn; Sum: Tổng.
~ End of Paper ~
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Combinatorics21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?Different way: Cách khác nhau.22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. H...
Đọc tiếp
Combinatorics
21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?
Different way: Cách khác nhau.
22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?
At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.
23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. How many even number(s) greater than 300 is / are there? (The repetition of digits is not allowed)
Digit: Chữ số; 3-digit number: Số có 3 chữ số; Even number: Số chẵn; Greater than: Lớn hơn; Repetition of digits is not allowed: Các chữ số không được lặp lại.
24. A flight of stairs has 10 steps. Peter can go up for 1 step, 2 steps or 3 steps each time. How many way(s) is / are there for Peter to go up the stairs?
Step: Bước; Way: Cách.
25. Numbers are drawn from 80 integers 20 to 99. At least how many number(s) is / are drawn at random to ensure that there are two numbers whose sum is 85?
Integer: Số nguyên; At least: Ít nhất; Random: Ngẫu nhiên; Ensure: Chắc chắn; Sum: Tổng.
~ End of Paper ~
choose 3 digits from 1, 3, 4, 5, 9 to form 3-digit numbers. how many number(s) that can be divisible by 5 is / are there?
choose 3 digits from 1, 3, 4, 5, 9 to form 3-digit numbers. how many number(s) that can be divisible by 5 is / are there?
Câu 1: How many distinct 3 - digit odd numbers can you make by using 0;1;2;4 and 5 ? (Giải thích rõ giúp mình)
Câu 2: How many distinct 4 - digit numbers are divisible by 2 can be form from digits 0;2;5;6 and 9 ? (Giải thích rõ luôn nha)
Câu 1 :
Có 2 cách để chọn chữ số hàng trăm ( trừ số 0 , 1 và 5 )
Có 2 cách để chọn chữ số hàng chục ( trừ một số ở hàng trăm và số 1 , 5 )
Có 2 cách để chọn chữ số hàng đơn vị ( trừ số 0 , 2 , 4 )
Như vậy có các số là :
2 x 2 x 2 = 8 (số)
Câu 2:
Có 2 cách để chọn chữ số hàng nghìn ( trừ số 0 , 2 và 4 )
Có 1 cách để chọn chữ số hàng trăm ( trừ một số ở hàng nghìn và số 0 , 2, 4 )
Có 1 cách để chọn chữ số hàng chục ( trừ một số ở hàng nghìn , một số ở hàng trăm và số 0 , 2 , 4 )
Có 3 cách để chọn chữ số hàng đơn vị ( trừ số 1 và 5 )
Như vậy có các số là :
2 x 1 x 1 x 3 = 6 ( số )
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how many distinct 4 digit numbers are divisible by 2 can be from digits 0, 2, 5, 6, 9