Answer:
16/33
Step-by-step explanation:
Tổng của cả 4 tấm thẻ là một số lẻ khi:
Có 1 thẻ là lẻ, 3 thẻ còn lại là chẵn, có: 6C1.5C3=60 cách
Có 3 thẻ là lẻ, 1 thẻ là chẵn, có: 5C1.6C3=100 cách
Suy ra có 160/11C4=16/33 cách
Answer:
17/18
Step-by-step explanation:
2
/18 + 15
/18
= 2
/18 + 15/
18
= 2+15
/18
= 17
/18
Answer:
80
Step-by-step explanation:
I believe it is C but I’m not sure
Assume a is not divisible by 10. (otherwise the problem is trivial).
<span>Define R(m) to be the remainder of a^m when divided by 10. </span>
<span>R can take on one of 9 possible values, namely, 1,2,...,9. </span>
<span>Now, consider R(1),R(2),......R(10). At least 2 of them must have the sames value (by the Pigeonhole Principle), say R(i) = R(j) ( j>i ) </span>
<span>Then, a^j - a^i is divisible by 10.</span>
