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A team of two students from an art school is to be selected to represent the school at a national event. The two students will be selected from the students in three classes that have no students in common. The three classes have 10 students, 8 students, and 7 students. If the two students must be selected from different classes, how many teams are possible?
How many different positive three-digit integers are there that have an odd hundreds digit?
How many integers between 100 and 1,000 have a hundreds digit that is even, a tens digit that is odd, and a non-zero units digit that is divisible by 3?
In a gift box, there are three types of gifts: 4 yoyo balls of different designs, 4 toys of different colors, and 3 candy bars of different flavors. In how many ways can 3 gifts be selected such that each one is out of each type of gift?
If an integer is chosen at random from the integers between 101 and 550, inclusive, what is the probability that the chosen integer will begin with the digit 1, 2 or 3, and end with the digit 4, 5, or 6?
Among 350 card, cards No.100 to No.299 are red. Among all red cards, cards that end with 4, 5, 6, 7, 8, 9 and 0 are round. What is the probability that a red round card is selected when randomly selecting a card from all 350 cards?
Among all the 24 different positive four-digit integers formed out of 6, 7, 8, 9, at which place will 8697 rank from the least to the greatest?
An artist has 3 hooks on the wall and 5 different pictures. How many different arrangements of 3 pictures can be formed if the artist puts one of the 5 pictures on each hook?

Quantity A

$$\frac{100!}{99!}$$

Quantity B

$$\frac{ (100!-99!)}{98!}$$


Quantity A

$$\frac{(5!+6!)}{(6!+7!)}$$

Quantity B

$$\frac{1}{6}$$


Quantity A

20!+19!+18!

Quantity B

400(18!)


Quantity A

$$\frac{23!}{(11!*13!)}$$

Quantity B

$$\frac{23!}{(10!*14!)}$$


In a kindergarten, three shorter kids sit in the first row, while four taller ones sit in the second row. In how many ways can they be arranged?
How many 6-digit integers greater than 321,000 can be formed such that each of the digits 1, 2, 3, 4, 5, and 6 is used once in each 6-digit integer?
The 9 computers in an office are to be interconnected by cables so that each computer is connected directly to each of the other computers. If each cable that connects a pair of the computers counts as one cable, how many cables are needed?
In a university, a certain committee consists of 6 faculty members, 4 administrators and 3 students. A subcommittee of 5 members will be selected from the committee. Professor Smith, who is one of the 6 faculty members, and Ms. Wilson, who is one of the 4 administrators must be on the subcommittee. The other 3 subcommittee members will be selected at random from the rest of the committee. How many different 5-member subcommittees can be selected?
Set K consists of 9 positive integers, 5 of which are prime numbers. How many subsets of K consist of 3 integers such that 2 integers are prime numbers and 1 integer is not a prime number?
How many different words that start with "mrt" can you get if you rearrange the letters of the word "merit"?
x and y are both positive integers, and 1 ≤ y ≤ 8, x < y, how many (x, y) coordinates are there?
Set A={12, 13, 14, 15, 16}

Set B={13, 14, 15, 16, 17}

How many different sums can be formed when selecting one number from each set and added together?

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