# Combinatorial number + reason - math problems

#### Number of problems found: 57

• Boys and girls
There are 11 boys and 18 girls in the classroom. Three pupils will answer. What is the probability that two boys will be among them?
• Three numbers
We have three different non-zero digits. We will create all 3 digits numbers from them to use all 3 figures in each number. We add all the created numbers, and we get the sum of 1554. What were the numbers?
• Each with each
Five pupils from 3A class played table tennis. How many matches did they play with each other?
• Five-digit numbers
How many different five-digit numbers can be created from the numbers 2,3,5 if the number 2 appears in the number twice and the number 5 also twice?
• Peaches
There are 20 peaches in the pocket. 3 peaches are rotten. What is the probability that one of the randomly picked two peaches will be just one rotten?
• Sweater
Dana confuses sweater and wool has a choice of seven colors. In how many ways can she choose from three colors to the sleeves?
• Triangles
Five sticks with a length of 2,3,4,5,6 cm. How many ways can you choose three sticks to form three sides of a triangle?
• Three students
Three students independently try to solve the problem. The first student will solve a similar problem with a probability of 0.6, the second student will solve at a probability of 0.55, and the third will solve at a probability of 0.04. The problem is reso
• Bridge cards
How many bridge hands are possible containing 4 spades,6 diamonds, 1 club, and 2 hearts?
• Dice
We throw five times the dice. What is the probability that six fits exactly twice?
• Subsets
How many 19 element's subsets can be made from the 26 element set?
• Test
The teacher prepared a test with ten questions. The student can choose one correct answer from the four (A, B, C, D). The student did not get a written exam at all. What is the probability that: a) He answers half correctly. b) He answers all correctly. c
• Sum on dice
We have two dice. What is the greater likelihood of fall a total sum 7 or 8 ? (write 7, 8 or 0 if the probabilities are the same)?
• Sum or product
What is the probability that two dice fall will have the sum 7 or product 12?
• Lines
How many lines can be draw with 8 points, if three points lie on one line and the other any three points do not lie on the same line?
• Three reds
What is the probability that when choosing 3 carats from seven carats, all 3 reds will be red?
• Roses 2
Aunt Rose went to the flower shop to buy a bouquet with three roses. The flower shop had white, yellow and red roses. How many different flowers bouquet can a flower make for Aunt Rose create? Write all the bouquet options.
• Math logic
There are 20 children in the group, each two children have a different name. Alena and John are among them. How many ways can we choose 8 children to be among the selected A) was John B) was John and Alena C) at least one was Alena, John D) maximum one wa
• First class
The shipment contains 40 items. 36 are first grade, 4 are defective. How many ways can select 5 items, so that it is no more than one defective?
• Two aces
From a 32 card box we randomly pick 1 card and then 2 more cards. What is the probability that last two drawn cards are aces?

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