# Combinatorics - practice problems

#### Number of problems found: 425

- Balls

From the bag with numbered balls (numbers 1,2,3,. ..20) we pick one ball. What is the probability of choosing a number containing 1? - Today in school

There are 9 girls and 11 boys in the class today. What is the probability that Suzan will go to the board today? - Telephone numbers

How many 7-digit telephone numbers can we put together so that each number consists of different digits? - Menu

On the menu are 12 kinds of meal. How many ways can we choose four different meals into the daily menu? - A pizza

A pizza place offers 14 different toppings. How many different three topping pizzas can you order? - Three-part novel

In how many ways can 7 books be stored on a shelf if there is one three-part novel to be placed side by side? - Election 4

In a certain election there are 3 candidates for president 5 for secretory and 2 for tresurer. Find how many ways the election may (turn out/held). - A student

A student is to answer 8 out of 10 questions on the exam. a) find the number n of ways the student can choose 8 out of 10 questions b) find n if the student must answer the first three questions c) How many if he must answer at least 4 of the first 5 ques - Mumbai

A job placement agency in Mumbai had to send ten students to five companies two to each. Two of the companies are in Mumbai and others are outside. Two of the students prefer to work in Mumbai while three prefer to work outside. In how many ways assignmen - A book

A book contains 524 pages. If it is known that a person will select any one page between the pages numbered 125 and 384, find the probability of choosing the page numbered 252 or 253. - Dd 2-digit numbers

Find all odd 2-digit natural numbers compiled from digits 1; 3; 4; 6; 8 if the digits are not repeated. - How many

How many double-digit numbers greater than 30 we can create from digits 0, 1, 2, 3, 4, 5? Numbers cannot be repeated in a two-digit number. - Tournament

Six teams entered the basketball tournament. How many matches will be played if each team has to play one match with each other? - Cards

From a set of 32 cards, we randomly pull out three cards. What is the probability that it will be seven kings and ace? - Seagull

Artificially created island in the shape of a circle with a radius of 50 m is overgrown with grass. The only exception is a landing area for helicopters in the shape of a rectangle measuring 15 m and 8 m. What is the probability that the flying seagull (w - First man

What is the likelihood of a random event where are five men and seven women first will leave the man? - Tokens

In the non-transparent bags are red, white, yellow, blue tokens. We 3times pull one tokens and again returned it, write down all possibilities. - White and black balls

There are 7 white and 3 black balls in an opaque pocket. The balls are the same size. a) Randomly pull out one ball. What is the probability that it will be white? We pull out one ball, see what color it is and return it to the pocket. Then we pull out th - Ice cream

Annie likes much ice cream. In the shop are six kinds of ice cream. In how many ways she can buy ice cream to three scoop if each have a different flavor mound and the order of scoops doesn't matter? - Cards

The player gets 8 cards of 32. What is the probability that it gets a) all 4 aces b) at least 1 ace

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