Math practice for 13 year olds - page 61 of 429
Number of problems found: 8569
- Spider fly legs
There are spiders and flies on the window. They have a total of 38 legs. How many spiders and flies are there if a spider has 8 legs and a fly has 6? Just give one solution. - Class weight average
There were 31 students in the class, and the arithmetic average weight was 43 kg. Calculate the average weight in the class if a student weighing 91 kg has been added to the class. - Salt solution
The 50% salt solution must be diluted with distilled water to make 20 liters of 35% solution. How many liters of original solution and how many liters of water do we need? - Plot plan price
On the 1:75 scale plan, the building plot is a rectangle with 60 cm and 50 cm dimensions. If 1 m² of land costs 80 euros, what is the price of the land? - Jane bought
Jane bought several identical lined notebooks, several identical squared notebooks, and several identical compasses at a stationery store. Two lined notebooks and two squared notebooks cost a total of 180 crowns. Two squared notebooks cost the same as thr - The ladder and wall
A 6.5-meter-long ladder rests against a vertical wall. Its lower end rests on the ground 1.6 meters from the wall. Determine how high the top of the ladder reaches and at what angle it rests against the wall. - Kite deltoid angles
A paper kite is shaped like a deltoid ABCD, with two shorter sides 30 cm long, two longer sides 51 cm long, and a shorter diagonal 48 cm long. Determine the sizes of the internal angles of the given deltoid. - Road gradient angle
On the traffic sign that informs about the road's gradient, the figure is 6.7%. Determine the slope angle of the path. What height difference is covered by the car that traveled 2.8 km on this road? - Hammer nail force
A hammer with a mass of 600 g hits the head of a nail at a speed of 5 m/s. If the nail penetrates 3 cm into the wall, what is the average resistive force of the masonry? - Battering ram force
A battering ram weighing 400 g falls from a height of 3 m. Upon impact, the stake hits a depth of 60 cm. What is the average force overcoming the soil resistance? - Pepa book pages
The book has 500 pages. Pepa has read half as many pages as he has left. How many pages did Pep read? - School trip ratio
One hundred seventy-five school pupils signed up for the school trip. The ratio of boys to girls was 9: 16. In the end, 19 registered students did not come on the trip, so the ratio of the number of participating boys and girls was 9: 17. How many boys an - Cylinder - curved area
The curved area of the rotary cylinder is three times greater than the area of one base of this cylinder. The radius of the base of the cylinder is 10 cm. What is the surface area of the cylinder? - Cable car lift
The cable car can take a given group of skiers out in 20 minutes and the lift in 30 minutes. How long will the lift and cable car take this group out simultaneously? - Milk butter kilograms
8 kg of butter is made from 20 hl of milk. How many kilograms of butter can be made from 450 l of milk? - Man train energy
A man with a mass of 80 kg crosses at a speed of 5 m/s through the car of a train traveling at 15 m/s. Indeed, the kinetic energy of a man: and, concerning the car b, relative to the surface of the earth, if the man is traveling in the direction of travel - Car kinetic energy
Determine the kinetic energy of a car with a mass of 800 kg if it travels at a speed: a) 10 m/s b) 20 m/s - Body kinetic work
What work must be done to bring a body of mass of 2 kg lying on a smooth horizontal plane from rest to a speed of 2 m/s? - Vinegar acetic acid Kitchen vinegar is an 8% solution of acetic acid in water. How many liters of acetic acid are needed to produce 275 liters of vinegar?
- Teacher paper correction
The new teacher corrects papers for 9 hours, and the older one fixes them in 6 hours. How much will they repair together?
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