Math practice for 13 year olds - page 49 of 414
Number of problems found: 8262
- Hectoliters - tank
A cylindrical tank with a base diameter of 1.2 m is supposed to hold 17 hectolitres of water. How many square metres of sheet metal are needed to make it, if 2% extra is added for joints and waste? - Isosceles
An isosceles trapezoid ABCD has a perimeter of 39 cm. Base AB is 7 cm longer than base CD, and each leg is 2 cm shorter than base CD. Calculate the length of base CD. - Determine the area
Determine the area of trapezoid ABCD, given that AB = 6 cm, the area of triangle ABC = 15 cm², the area of triangle BCD = 20 cm², and AB ∥ CD. - Cookies - price
The price of cookies was increased from 16 crowns to 17 crowns. By what percentage did the price increase? - Two cuboids
A cuboid has dimensions of 2 m × 3 m × 4 m. We increase the length of all edges by 50 cm. 1. By what percentage does the surface area of the cuboid increase compared to the original? Round the result to the nearest whole percent. 2. By what percentage doe - Condensation
How many litres of water must be evaporated from 400 kg of a 10% soda solution to obtain a 16% solution? - Boxes
Petra has planted flowers in two boxes in the shape of a cube. The first box has an internal dimension of 70 cm and the second 5 dm. She wants to make one box in the shape of a cuboid, into which she could transplant both flowers from these boxes. The new - Diagonals
Construct a rhombus whose diagonals have lengths of 10 cm and 8 cm and make an angle of 115° with each other. - Graduation of the track
The gradient of the track is 9 per mille, and the distance along the slope [AC] is 560 m. Determine angle alpha and the distance [AB], which is the height between A and B. A / | B/____________C - Heating water
5 kg of water warmed up by 10 °C. How much heat did the water absorb? (Remember that 1 kg of water requires 4,200 J of heat to raise its temperature by 1 °C.) - Dividing Fruit by Ratio
60 kg of fruit were divided between the KOP store and the FRESH store in a ratio of 2:3. How many kilograms did the FRESH store receive? - Reading a Book Faster
Jana received a new book. She wants to read it in 8 days. If she read 6 more pages a day, she would finish the book two days earlier. How many pages does the book have? - Running Distances of Friends
Three friends, Jana, Jannet, and Adriana, like to run. On Sunday they all went for a run. Jana ran twice as many kilometres as Jannet. Adriana ran 3 kilometres more than Jannet. How many kilometres did Adriana run if the friends ran 11 kilometres in total - In an electrical 3
In an electrical circuit, R₁ = 4,000 Ω, R₂ = 8,000 Ω, and R₃ = 6,000 Ω are connected in series. The power supply has a voltage of 100 V. Calculate the voltage across R₁, R₂, and R₃. - Raspberry juice
How much will the scout leader pay for drinks for the children, if a third of the children had raspberry juice for 10 CZK, half of the children had sparkling water for 15 CZK, and the remaining 4 children had kola for 20 CZK? - Workers
The first worker can complete a job in 40 hours, the second in 50 hours, and the third in 80 hours. How long will it take them to complete the job if they all work together? - RR trapezoid
Given an isosceles trapezoid ABCD with bases |AB| = 36 m and |CD| = 200 dm, and leg |BC| = 10 m. Calculate the area and perimeter of the trapezoid and the length of diagonal AC. - A bicycle
Martin sold a bicycle at a profit of 10%. Had it been sold for $75 more, the profit would have been 16%. Find the cost price of the bicycle. - February sales
A company earned only four fifths in February of what it earned in January. By what percentage did the company earn more in January than in February? - Dependent variables
A printer prints k sheets in n seconds (k, n ∈ ℕ). Express the number of sheets that the printer prints in 5 minutes in terms of k and n.
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