Reason - 8th grade (13y) - math problems
- 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?
How probable is a randomly selected three-digit number divisible by five or seven?
- Five letters
How many ways can five letters be arranged?
- Large family
The average age of all family members (children, mother, father, grandmother, grandfather) is 29 years. The average age of parents is 40 years, grandparents 66 years and all children are 5 years. How many children are there in this family?
- Sweets, candy
Grandfather gave out sweets to four children. At the last moment, two more children came, so in order to have them all the same, each of the four children would receive four candies less than they would have received if they had not. How much did my grand
There are two leaders in the tourist group, with an average age of 30 years and several children with an average age of 10 years. The total age of the group is 12 years. How many children are in the group?
- Aircraft angines
The two engines of the aircraft are enough to supply the fuel for five hours of operation. However, one of the engines has a malfunction and thus consumes one-third more fuel. How long can the plane be in the air before it runs out of fuel? After an hour
- Magnitude of angle
What magnitude has an obtuse angle enclosed by the hands of clocks at 12:20 hours?
There were 22 liters of milk in three containers. There was 6 liters more in the first container than in the second. After pouring 5 liters from the first container into the third container, the same quantity of milk is in the second and third container.
- Pairs of socks
Ferdinand has twelve pairs of socks, one sock is leaky. What is the probability of putting on a leaky sock?
- Christmas or Easter
Please calculate this example by the Venn equation. They asked 73 students whether they like Christmas or Easter. 34 of them like one of the holidays. 39 loves Easter. There are twice as many students who wish both holidays than those who only love Ea
How many three-digit natural numbers are divisible by 25?
- Mysterious area
The trapezoid ABCD is given. Calculate its area if the area of the DBC triangle is 27 cm2.
- Intelligence test
Paľo, Jano, Karol, and Rišo were doing an intelligence test. Palo correctly answered half of the questions plus 7 questions, Jano to a third plus 18 questions, Karol to a quarter plus 21 questions and Risho to a fifth plus 25 questions. After the test, K
- Bdf tablet
Detective Harry Thomson has come across a surprising mystery. As part of the weekend's action, the tablet he looked for dropped by 30%. He also recommended this bargain to his friend. However, it came to the shop on Monday, and the tablet was 30% more exp
Vladimir likes to draw rectangles. Yesterday he created all rectangles that had sides in centimeters and a circumference of 18 cm. How many rectangles of different dimensions have been drawn?
- Irregular pentagon
A rectangle-shaped, 16 x 4 cm strip of paper is folded lengthwise so that the lower right corner is applied to the upper left corner. What area does the pentagon have?
How many different rectangles can be made from 60 square tiles of 1 m square? Find the dimensions of these rectangles.
- Two integers
Two integers, a and b, have a product of 36. What is the least possible sum of a and b?