Reason - practice for 13 year olds - page 25 of 40
Number of problems found: 794
- Perpendicular 5865
We cut the cube with two mutually perpendicular cuts, each parallel to one of the cube's walls. By what percentage is the sum of the surfaces of all cuboids created in this way greater than the surface of the original cube? - Regularly 5036
Out of 129 1st-year students, 116 students go to lunch or dinner regularly, and 62 students go to one of these meals at most. At the same time, 46 students go to lunch more than to dinner. How many students go to lunch and dinner, how many go to dinner, a - Reappeared 3152
At 6:15, a ghost conjured a clock that showed the correct time. At that moment, the hands on the clock began to move at the correct speed but in the opposite direction. The ghost reappeared at 7:30 p.m. What time was the clock showing at this moment? - Grandfather's 2876
To the question: How old are your two grandchildren? The grandfather answers: if I add their sum to the product of the numbers that determine their age, I get 14. How many years have grandfather's grandchildren? Think only for years. - Sweets
Three chocolate and seven cakes cost 85 CZK. Two chocolates and six cakes cost 86 CZK. How much are five chocolates and nine cakes? I wonder how to get the result, but only by logic, without using a system of equations. - Individual 4881
There are 32 rooms in the hostel. Some have double beds, others have four beds and the rest have 7 beds. There are a total of 139 beds in the hostel. How many are there if a two-digit number gives the numbers of individual species? - Same remainder
Find the greatest number that will divide 43, 91, and 183 so as to leave the same the remainder in each case. - Smoker male
For a person selected randomly from a certain population, events A and B are defined as follows. A = event the person is male B = event the person is a smoker. For this particular population, it is found that P(A ) = 0.53, P(B) = 0.15, and P(A n B ) = 0.1 - Apples investment
The merchant bought a certain amount of apples and paid one denarius for every seven apples. The next day he sold all the apples for one denarius for five pieces and earned 12 denarii. How many apples did he originally buy, and how many did he have to inv - 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? - 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 - Three dice
The player throwing the three dice asked G. Galilei: "Should I bet on the sum of 11 or the sum of 12?" What did Galilei answer him? Hint: write down all three triples of numbers that can be thrown, have a total of 11, have a total of 12, and compare proba - Three numbers
We have three different non-zero digits. We will create all three digits numbers from them to use all three figures in each. We add all the made numbers and get the sum of 1554. What were the numbers? - Lunch
Seven classmates go every day for lunch. If they always come to the front in a different order, will it be enough school year to take of all the possibilities? - Testing
Students in high school have 10 points for each good-solved task. Five points deduct the wrong answer. After solving 20 tasks, student Michael had 80 points. How many tasks did he solve correctly, and how many were wrong? - Nectar
Nectar collected by bees contains 70% water. The nectar of the same process produces honey which has 19% water. How many kilograms of nectar do bees need to collect to make 1 kg of honey? - Trains
On a double-track line between stations, K and M went against each other two trains. The first train passed the distance between stations for 3.5 hours, and the second, which had an average speed of 12 km/h more, passed for 3.05 hours. Calculate the dista - Tractors
Fields go plow two tractors with various performances. The first tractor plows the whole field in 11 hours. The second tractor plows the whole field 19 hours longer. How long does it take to plow the whole field with two tractors? - Three-digit 80768
Nikola had one three-digit and one two-digit number written in her notebook. Each of these numbers was made up of different digits. The difference in Nicole's numbers was 976. What was their sum? - Percentage 65844
Mr. Josef sold home-grown potatoes at 79 cents per kilogram. When he had the last 5 kg, he told the customer: collect them all for 3 euros! By what percentage did Mr. Josef reduce the potatoes?
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