# Combinatorics - math word problems

#### Number of problems found: 332

• Research in school For particular research in high school, four pupils are to be selected from a class with 30 pupils. Calculate the number of all possible results of the select and further calculate the number of all possible results, if it depends on the order in which th
• Three-digit numbers We have digits 0,1,4,7 that cannot be repeated. How many three-digit numbers can we write from them? You can help by listing all the numbers.
• Probability of failures In certain productions, the probability of failures is 0.01. Calculate the probability that there will be more than 1 failure among the 100 selected products if we return the selected products to the file after the check. How large must the group of people be so that the probability that two people have a birthday on the same day of the year is greater than 90%?
• All use computer It is reported that 72% of working women use computers at work. Choose 3 women at random, find the probability that all 3 women use a computer in their jobs.
• Gold, silver, bronze How many ways can we divide gold, silver, bronze medails if there are 6 people competing?
• The manufacturer The manufacturer found that 3% of the plates produced had a malfunction. Of the compliant, 75% are first and 25% second. What is the probability of producing first and second class plates?
• Five letters How many ways can five letters be arranged?
• The test The test contains four questions, and there are five different answers to each of them, of which only one is correct, the others are incorrect. What is the probability that a student who does not know the answer to any question will guess the right answer
• Double probability The probability of success of the planned action is 60%. What is the probability that success will be achieved at least once if this action is repeated twice?
• Alarm systems What is the probability that at least one alarm system will signal the theft of a motor vehicle when the efficiency of the first system is 90% and of the independent second system 80%?
• Corona again If the population on long island is 7.75 million and the coronavirus has affected 22,178. What percent of the population is affected. (looking for 1 in? If possible)
• Chess competition 4 chess players took part in the competition. How many tournaments have taken place if every chess player has fought everyone once?
• Table and chairs Four people should sit at a table in front of a row of 7 chairs. What is the probability that there will be no empty chair between them if people choose their place completely at random?
• Fall sum or same Find the probability that if you roll two dice, it will fall the sum of 10, or the same number will fall on both dice.
• Birth Let's assume that the probability of the birth of a boy and a girl in the family is the same. What is the probability that in a family with five children, the youngest and oldest child is a boy?
• Divide How many different ways can three people divide 7 pears and 5 apples?
• Fruits In the shop sell 4 kinds of fruits. How many ways can we buy three pieces of fruit?
• Bouquets In the flower shop they sell roses, tulips and daffodils. How many different bouquets of 5 flowers can we made?
• Twelve flowers A florist has roses, tulips, daffodils, and carnations to use in flower arrangements. If she were to make an arrangement using 12 flowers, how many different combinations of these 4 types of flowers would be possible?

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