Math practice for 13 year olds - page 312 of 423
Number of problems found: 8459
- Storm
So far, a storm has traveled 35 miles in 1/2 hour in a direction straight to the observer. If it is 5:00 PM, and the storm is 105 miles away from you, at what time will it reach you? Explain how you solved the problem.
- Travel 4858
How long will a 1 km long tunnel take to travel at a speed of 100 km per hour?
- Runners 4857
Two runners run on a 3200m oval track, one running at 12 km/h and the other at 8 km/h. How long does it take for the first runner to finish the second one?
- Complete 4849
The first sluice empties a complete pond in 45 days. If 2/3 of the pond is drained in 15 days, a second sluice is still needed for ten days. How many days would it empty itself through just the second sluice?
- Salt
Seawater containing 5% salt. How many kilograms of fresh water is necessary to pour into 40 kg of seawater so that the salinity falls to 2%?
- Trapezoid
How long are the trapezoid bases with an area of 24 cm² and a height of 3 cm? One base is three times longer than the shorter.
- Megapascals
What is the area of cross-section of the piston if the force of 300 kN produces a pressure of 5 MPa?
- Rope
How many meters of rope 10 mm thick will fit on the bobbin diameter of 200 mm and a length of 350 mm (the central mandrel has a diameter of 50 mm)?
- Numerically 4839
Calculate the diagonal of such a square, which holds that its area is equal to its perimeter (without considering units numerically ...).
- Traveling 4836
A passenger car traveling at a speed of 60 km/h arrived from place A to place B one and a half hours earlier than a truck traveling at 40 km/h. How far apart are placed A and B, and how long did the car travel?
- Bags
The first bag weighs 18 kg, the second bag is one-third lighter than the first, and the third bag has three times less than the weight of all three bags. Determine their weights.
- Center of gravity
In the isosceles triangle ABC the lengths of AB and the height to AB is the ratio of 10:12. The arm has a length of 26 cm. If the center of gravity is T, find the area of the triangle ABT.
- Bicycles
You're the owner of the transport's learning playground. Buy bicycles of two colors, but you've got to spend accurately 120000 CZK. The Blue bike costs 3600 CZK and the red bicycle 3200 CZK.
- Family
Mom is 42 years old, and her daughters are 13 and 19. After how many years will a mother become as old as her daughter together?
- Tree shadow
The shadow of the tree is 16 meters long. The shadow of a two-meter-high tourist sign beside standing is 3.2 meters long. What height is a tree (in meters)?
- Beginning 4820
Karel saved SKK 12,000 in the savings bank at the beginning of the year. At the end of the year, the savings bank credited him with SKK 1,680. At what annual interest rate did Karel have the deposit in the savings bank?
- Rectangular meadow
Divide the rectangular meadow with dimensions of 1280m and 320m into a square shepherd with the longest possible side of the square. How many square pastures did you divide the meadow?
- Hectoliters 4817
There are 1.5 hectoliters of rainwater in the barrel. Two-fifths of the water passed from the barrel while watering the garden. How many liters of water remained in the barrel?
- Equation: 4816
Solve the equation: 1/c - 3/(2c) = 3/4
- Collected 4815
Pupils collected a total of 42 kg of apples. Peter harvests half as much as Zuzka and Martin, a third less than Petr. How much did each of them harvest?
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