Reason - practice for 14 year olds - page 9 of 40
Number of problems found: 798
- Five-digit number
Anna thinks of a five-digit number not divisible by three or four. If he increments each digit by one, it gets a five-digit number divisible by three. If he reduces each digit by one, he gets a five-digit number divisible by four. If it swaps any two digi - No solutions
Why does the equation 9-2x-9-16x=-14x-7-4x-11 have no solutions? - Pigs
A buyer said, "I want to buy 100 pigs for 100 denarii. An adult pig costs ten denarii, a sow five denarii, and two little piglets are worth one denarius. " How many pigs, cows, and piglets could he buy for exactly 100 denarii? - Arithmetic 40671
The number 20 is the arithmetic mean of the eight numbers. Determine their sum.
- Average weight
Mom bought six apples with an average weight of 130 g - If she took one apple out of the bag, the average weight of the remaining apples changed to 140 g. What was the weight of the removed apple? - Arithmetic 40431
Fill the numbers in the place of the asterisk to form an arithmetic sequence. (2, *, 5, *, 8, 9.5,11) - The family
How old is a mother if she is four times older than her daughter, and five years ago, she was even seven times older than her daughter? Today, a son is 30 years younger than a father. Seven years ago, a father was seven times older than a son. How old is - Karolína
Carolina chose five bodies from the kit - white, blue, and gray cubes, a blue cylinder, and a white triangular prism. How many different roof towers can be built one by one if all the blue bodies (cube and cylinder) are not placed on top? - Two grandmothers
Two grandmothers went to the market to sell eggs, and they had 100. When they sold all the eggs, they made the same money. The first grandmother said to the second, "If I sold my eggs for your price, I would earn 15 crowns. " The other grandmother replied
- Three-digit 38371
How many odd three-digit numbers can you make of the five cards with the numbers 1, 2, 3, 5, and 6? - Two ports
Between the ports of Mumraj and Zmatek, two ships commute along the same route. They spend negligible time in ports, turn around immediately, and continue sailing. At the same time, a blue ship departs from the port of Mumraj, and a green ship departs fro - Coloured numbers
Mussel wrote four different natural numbers with colored markers: red, blue, green, and yellow. When the red number divides by blue, it gets the green number as an incomplete proportion, and yellow represents the remainder after this division. When it div - Squirrels
The squirrels discovered a bush with hazelnuts. The first squirrel plucked one nut, the second squirrel two nuts, and the third squirrel three nuts. Each new squirrel always tore one nut more than the previous squirrel. When they plucked all the nuts from - Barborka 36393
Adela and Barbora have a total of 34 candies. If Barbora gives Adela 2 candies, they will have the same. How many candies does Adela have, and how many Barbora?
- Defective 35831
Among the 24 products, seven are defective. How many ways can we choose to check a) 7 products so that they are all good b) 7 products so that they are all defective c) 3 good and two defective products? - Round table
Eight people are sitting at a round table. In how many ways can they be seated around the table? - Double-track line
A 160 m long passenger train runs on a double-track line in one direction at a constant speed of 54 km/h, and a 240 m long express train in the opposite direction. a) How fast is the express train if passing the passenger train driver for 6 s? b) How long - Following 34291
The following holds for two non-empty sets, A and B: A ∪ B has 16 elements, A ∩ B has 11 elements, and the set A - B is empty. How many elements does set B-A to have? - One dice
Calculate the probability of one dice roll with the numbers 1, 2, 3, 4, 5, and 6 on the walls. Write the results in a notebook in the shape of a fraction in the basic form: 2/3. a The number 1 falls on the cube. b, The number 5 falls on the cube. c, An ev
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