Math practice for 13 year olds - page 347 of 424
Number of problems found: 8472
- Candy
The price for 1 kg of more expensive candy is 125 CZK. The price for 1 kg of cheaper candy is 100 CZK. We make two different blends of candy. And now. The second blend contains 2 kilograms of more expensive candy and several kg of cheaper candy. The price - Solution dilution
1.5 kg of a 20% NaCl solution should be diluted to a 10% solution with water. How much water will we need, and how many kilograms of diluted solution will we get? - Alcohol mixing
How many liters of 80% alcohol need to be mixed with 4 liters of 40% alcohol to get 70% alcohol? How many liters of 70% solution do we get? - Two numbers sum
The sum of the two numbers is 52.5. The first number makes up 75% of the second number. Specify both numbers. - Solution
What amount of 80% solution and water is needed to mix to obtain two liters of 60% solution of this mixture? - Parallelogram sides
In the parallelogram ABCD, the side AB is three times longer than the side BC. The perimeter of the parallelogram is 20 cm. Find the lengths of the sides of the parallelogram. - Savings distribution
Milo has 84 euros. He gave his brother 20% of his savings and his sister 25%. Find how much money each has. - Two-digit numbers
How many two-digit numbers can you create from the digits 7,0,1 and 5 if the numerals can be repeated? - Mr. John
Mr. John wants to buy winter apples Spartan. There are two ways to buy: 1) buy apples at the marketplace, where 1 kg costs 15 CZK. 2) Bring the car to the agricultural farm, where the apples are sold for 9 CZK per kilogram. However, he must pay CZK 150 fo - Beam on platform
A homogeneous wooden beam of length 6.00 m and mass 72.0 kg lies on a horizontal platform high above the ground and overhangs by 1.80 m over the edge of the platform a) Decide whether a person with a mass of 60.0 kg can stand on the overhanging end of the - Mr. Liška
Mr. Liška decided to replace the floors in some rooms of his flat. a) The kitchen is a rectangle with sides 180 cm and 420 cm. How many square tiles with a side of 20 cm long will he need? b) How many packages of tiles must he buy, if in one package there - Tiles path
A rectangular park measures 24 m X 18 m. A path 2.4 m wide is constructed all around it. Find the cost of paving the path with cement tiles of size 60 cm X 40 cm at the rate of $5.60 per tile. - Digging
A pit is dug in the shape of a cuboid with dimensions 10mX8mX3m. The earth taken out is spread evenly on a rectangular plot of land with dimensions of 40m X 30m. What is the increase in the level of the plot? - Fog
The car started in fog at a speed of 30 km/h. After a 12-minute drive, the fog dissipated, and the driver drove the next 12-minute distance, 17 km. The driving conditions deteriorated during the last 17 km, and the driver drove at 51 km/h. a) Calculate th - Sum probability
Natural numbers 4,5,7,11,12 are given. Calculate the probability of the event that the sum of three randomly selected numbers is less than 22. - Class 9A
On the final certificate, one-quarter of the class 9 A marked “C” in mathematics, the seventh mark “C” from the Czech language, and two students failed in chemistry. How many students attend class 9 A? - Fit ball
What is the size of the surface of a Gymball (FIT - -ball) with a diameter of 65 cm? - Pipe surface
Calculate the surface area of a pipe section if: outer diameter = 40 cm; length = 3 m - Water reservoir
The water reservoir is filled with one pump for four days by the second one for nine days. An outlet can drain the tank in 12 days. How long does it take to fill the reservoir if both pumps are running and not closed outlet channels? - Shadow and light
Nine meters height poplar tree has a shadow 16.2 meters long. How long does shadow have at the same time as Joe if he is 1,4 m tall?
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