Math practice for 13 year olds - page 57 of 423
Number of problems found: 8458
- Mathematics 83190
The number of students studying teacher studies in mathematics has decreased in the last twenty years in a ratio of 2:10. How many students are studying teacher studies now when twenty years ago there were 50?
- Percentages 83188
There are 10 bags displayed in the store, 2 of which have a hidden error. Buyers randomly choose one bag. Express in percentages the probability that they will buy the bag without a mistake.
- Daffodils 83181
The spring bouquet consists of 13 daffodils and 8 tulips, and the other 30% are freesias; how many flowers are there in total?
- The balance - the lever
For the lever to be balanced, the arms' lengths must be inversely proportional to the weight ratio of the weights suspended on these arms. Complete the data: 30 cm, 10 cm, 4 kg, and m2 kg.
- Original model
When drying, the modeling mass loses 36% of its original volume. If the cube's volume is 5.12 dm³ after drying, what was the original length of the edge?
- Apprentice 83169
The master gave the apprentice the task of dividing the 28 m long electric cable into two parts so that the second part was 2.5 times larger than the first. How long were the cable sections supposed to be?
- Afternoon 83168
In the morning, 6 liters more water was in the green canister than in the blue one. In the afternoon, the gardener poured 1 liter of water from the green canister into the blue one. There was then twice as much water in the green canister as in the blue o
- Successful 83167
Eighth-grade test results: 8D =? 8B = 47 8A = 44 8E = 37 8C = 28 Class 8A achieved exactly the average result. How many points did the winning class 8D get? By what % is class 8B more successful than class 8C?
- Increased number
A farmer has 250 cows. One cow has 5m² in the cowshed. When their number increases by 26, how much m² will the space for one cow decrease?
- Enlarges 83161
Enlarges the number 148 in a ratio of 13:4
- Overhangs 83158
The area of a right triangle ABC is 346 cm2, and the angle at vertex A is 64°. Calculate the lengths of the overhangs a and b.
- Hypotenuses 83154
In a right-angled triangle ABC with a right angle at the vertex C, the magnitudes of the hypotenuses are given ta=5, tb=2√10. Calculate the side sizes of triangle ABC and the circle's radius described by this triangle.
- Circumscribed 83152
Given is an isosceles triangle whose base is 8 cm, and the sides are 15 cm long. Calculate the area of the triangle and the radius of the inscribed and circumscribed circle.
- Students 83149
There are 30 students in the class. Five had a mark three — other twos and ones. The average grade was 1.9. How many students got mark one?
- Braking 83146
A car of mass m=1t moves at a speed v0=54 km/h. What braking force must be exerted to bring the car to a stop in 10 seconds, and how far will the car travel in this time?
- Tetrahedron 83144
A container shaped like a rotating cylinder with a base radius of 5 cm is filled with water. If a regular tetrahedron with an edge of 7 cm is immersed in it, how much will the water level in the container rise?
- Basketball 83137
In the basketball game, the players threw 37 times, including 2-pointers and 3-pointers, for a total of 82 points. How many were 2 points, and how many were 3 points?
- Republican 83136
In the republican calendar (used in France from 1793 to 1805), one full day was divided into 10 hours; each hour had 100 minutes, and each minute had 100 seconds. What time would the clock show at that time when today's clock reads 15:36?
- Dimensions of an aquarium
The large aquarium is shaped like a cuboid and has dimensions in the ratio 5: 7: 4. The sum of the lengths of all edges is 96 dm. How many liters of water will be in the aquarium if it is filled to four-fifths?
- Skiing and sledding
Behind the pond, the cat Miki is skiing and Bobo is sledding down a 300-meter-long slope. Careful Bobo can go down the slope in one minute. How many km/h faster does Miki go down the hill than Bobo if he is down 20 seconds earlier?
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