Math practice for 13 year olds - page 80 of 435
Number of problems found: 8682
- Combined 81039
Katka has k marbles, Petra has 20 more marbles than Katka, and Lenka has 30 marbles less than Petra and Katka combined. How many marbles do they all have in total? - Instantaneous 81036
Calculate the instantaneous free fall velocities at the end of the 1st, 3rd, 5th, and 7th seconds. Compile the results in a table. - Calculate 81034
Calculate the volume of the spherical segment and the surface area of the canopy if the radius of the sphere is r=5cm and the radius of the circular base of the segment ρ=4cm. - Circumscribed - sphere
A cube with a volume of 4096 cm³ is described and inscribed by a sphere. Calculate how many times the volume of the circumscribed sphere is greater than the inscribed sphere. - Thanks 81022
Pavla is 2x older than Irena. Four years ago, Pavla was 6 times older than Irena was then. In how many years will the ages of Pavla and Irena be in the ratio of 4:3? Thanks - Everyone's 81021 There are 10 students in the drama club. We count everyone's age in whole years. The average age of the girls is 12.25 and the boys 12.5, and the average age of all is 12.3. How many girls and how many boys are there in the class?
- Possible 81020
The front of the cycling peloton travels at an average speed of 48 km/h. The cyclist with the green T-shirt lost 5 minutes when he fell. What speed must he drive if he wants to reach the front of the peloton in twenty minutes? Possible?
- Windbreaker 81000
Before the season, the windbreaker became more expensive by 30% to the amount of 80.60. How much was it before the price increase? - Follows: 80998 The three friends divided the money earned as follows: Tonda got 2/5, Karel 2/9, and Jirko took the rest of CZK 102. How much did each of them earn?
- Siblings 6
Siblings Martin and Jitka decided to visit a castle that is 10 km away from their home. Martin left at 7:30 and walked at a speed of 4 km/h. Jitka rode her bicycle behind him an hour and a half later and rode at a speed of 16 km/h. Did Jitka catch up with - Subtracting 80967
Martin thinks of a number. Subtracting two-thirds of it and adding the number 8 gives the number 40. What is the original number that martin was thinking of? - Visitors 80966
The second weekend saw 20% fewer visitors than the first. Over the two weekends, the number of visitors was 27,500. How many visitors came on the second weekend? - Through 80963
The fire tank is filled with three inlets, each flowing 6 liters per second in 12 hours. How long will it take to fill if 8 liters per second flow through each of them? - Five-minute 80951
Karel has an average grade of exactly 1.12 from five-minute episodes. Prove that at least 22 of them have one. - The perimeter
The perimeter of the base of a regular quadrilateral pyramid is the same as its height. The pyramid has a volume of 288 dm³. Calculate its surface area round the result to the whole dm².
- Interest 80867
How much is the deposit? Which at an interest rate of 3.75%p. a., will it increase by 25 euros in one year? - Daughter 80855
Mother and daughter walked side by side. They walked 378 meters, and the mother took 840 steps. Before the mother takes 3 steps, the daughter takes 4 steps. What is the mother's stride length? How many steps did the daughter take? - Perimeter 80853
The lengths of the sides of the triangle are in the ratio 7:6:4. The shortest side is 36 cm. What is the perimeter in cm of this triangle? - Equilateral 80851
Kornelia cut off the colored part from the equilateral triangle. The shortest side of the colored triangle is 1/3 the length of the side of the original triangle. Calculate what part of the triangle she cut off. - Purchase 80850 Janka and Danka together paid €132 for the purchase. However, Jana paid five times more than Danka. How many euros did Janka pay, and how much did Danka pay?
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