Math practice for 13 year olds - page 73 of 422
Number of problems found: 8432
- Perimeter 81600
The radius of the circular bed is 2 m. Around it is an area filled with sand, the border of which is formed by the sides of a square with a length of 5 m and the bed's perimeter. Calculate the volume of the area covered with sand.
- Forty-five 81599
Lukas left the Tereza cottage and walked at an average 4 km/h speed. Forty-five minutes later, Jakub followed him on a bicycle from the same cottage. He followed Lukas's route and caught up with him after 20 minutes. What was Jakub's average speed?
- Periodic function
Simplify by using periodicity cos 1125°
- Rectangle's 81596
The rectangle has a perimeter of 30 cm. The ratio of its sides a: b=2:3. Calculate the sides' lengths and the rectangle's area.
- Intersection 81594
Given a trapezoid ABCD and the sizes of the interior angles. Angle SDC 32° SAD angle 33° SDA angle 77° Angle CBS 29°, where S is the intersection of the diagonals. What is the size of the angle BSA?
- Deposited 81585
Mr. Investor deposited half of his money in the bank at 5% interest. He invested the other half in bonds with 7% interest. How much money did he invest when his annual profit was CZK 600?
- Restaurant 81584
Four students were paying the bill in the restaurant. Jan paid 7 rums and 20 beers, Adam 20 rums and 7 beers, Víťa 12 rums and 25 beers, and Dan 25 rums and 12 beers. Jan paid 20% less than Adam. By how much % less did Víťa pay than Dan?
- Distance 81578
The express train leaves place A at 19:20 and arrives in town B at 20:24. The average speed of the express train is 15 m/s. What is the distance between cities A and B?
- Downstream 81577
The water in the river has a speed of 4.8 km/h relative to the bank. A boat in still water has a speed of 12.6 km/h. a) What is the boat's speed relative to the shore if it is sailing downstream and upstream of the river? b) What path will the boat travel
- Determine 81572
In one triangle, one angle is 43°, and the second is 15° less than the third. Determine the unknown angles of the triangle.
- Propagation 81568
A cannon fired at a distance of 2720 m from the observer. The sound of the shot was heard by the observer 8 seconds after the flash. Calculate the speed of sound propagation in the air if we assume that the observer saw the flash at the same time as the s
- Discounted 81567
A trip to Egypt was discounted by one-third of the price at the last minute. The discount was 5760 CZK. What was the original price of the tour?
- Students 81563
Sixth, seventh, and eighth graders took part in the school trip. Sixth graders were 5 more than seventh graders, and eighth graders were 3 less than sixth graders. How many sixth graders were on the trip if there were 73 students in total?
- Calculate 81560
The cone's surface is 75.36 cm, and the radius is 3 cm. Calculate the volume of the cone.
- Together 81559
A car drives for an hour on the highway at a speed of 100 km/h, then for half an hour at a speed of 80 km/h, and for another half hour in the field at a speed of 20 km/h. What track did he run together? What is the average speed of the car?
- Proportion 81558
Pour 9 dl of dye into 100 liters of water. What will be the proportion of dye in the resulting mixture? Express as a percentage.
- Circumference 81557
Calculate how many volleyballs with a circumference of 65 cm fit into a cube-shaped rack whose edge is 100 cm long.
- Five-quarters 81556
Add one-third to five-eighths and divide the result by the sum of the numbers five-quarters and two-thirds.
- Necessary 81554
It is necessary to determine the number whose double is reduced by 15 equals the number 5.
- Calculate 81553
The picture puzzle made of wooden cubes weighs 0.792 kg. One cube has an edge length of 4 cm and a weight of 33 grams. Find out how many cubes make up a puzzle and calculate the wood density in kg/m³.
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