The fourth question is to ask you 20
The third question is about the probability that all three coins are randomly thrown face up. Without permutation and combination, the probability of each face facing up is 0.5. According to the principle of multiplication, the probability that all three coins face up is 1/8.
The second question is that there are five letters L, O, G, I and C randomly arranged to form five letters, asking you the probability of forming the word logic.
This is arranged, which is what you call Pmn. For them, all the possibilities are p 5 5= 120, and only one is logic, so choose a.
The first question, the four-digit 3589 has this characteristic. The number of digits in each digit is different, and it increases from thousands to one digit in turn. How many digits in an integer between 4000 and 5000 match the characteristics of the number 3459?
Because the number is between 4000 and 5000, the thousand digits can only be 4, and the digits of 100 and 10 are to be determined. The number greater than 4 is 5 6 7 8 9. Just choose three of these five numbers and arrange them in the hundredth place in descending order. We can definitely arrange a number that meets the requirements, using the combination C5 3 = 10, so it is10.
I hope it helps you. You can ask questions