# Examples for 8th grade - page 74

- Cuboid and ratio

Cuboid has dimensions in ratio 1:2:6 and the surface area of the cuboid is 1000 dm^{2.}Calculate the volume of the cuboid. - Donuts

In the dining room at one table sit Thomas, Filip and Martin. Together they eat 36 donuts. How many donuts eaten everyone, when Filip ate twice as much as Thomas and Martin even half over Filip? - Flowerbed

In the park there is a large circular flowerbed with a diameter of 12 m. Jakub circulated him ten times and the smaller Vojtoseven times. How many meters each went by and how many meters did Jakub run more than Vojta? - Collecting

For the first week of material collection events are picked up at the school 850 kg of paper and 305 kg of rags which represented 55% of total collection for 14 days. How many kilograms of secondary raw materials were handed over totally? - Unknown number 24

f we add 20, we get 50% of its triple. What is this unknown number? - Rhombus 4

Circumference of the rhombus is 44 cm, its height is 89 mm long. Calculate its content area. - Simply equation

Solve this equation for x: ? - Cube surface area

The surface of the cube was originally 216 centimeters square. The surface of the cube has shrunk from 216 to 54 centimeters sq. Calculate how much percent the edge of the cube has decreased. - Sales off

Calculate what was the original price of the good, if the price after discount 40% and the subsequent rise of 30% is 4000 USD. - Circle - simple

Calculate the area of a circle in dm^{2,}if its circumference is 31.4 cm. - Water channel

The cross section of the water channel is a trapezoid. The width of the bottom is 19.7 m, the water surface width is 28.5 m, the side walls have a slope of 67°30' and 61°15'. Calculate how much water flows through the channel in 5 minutes if the water flow - Aunt

Annie aunt is 35 years old, Annie is 14 years. For how many years will aunt have twice as many years as Annie? - Percent

Calculate how many % is the number 26.25 less than the number 105. - Disc

Circumference of the disk is 78.5 cm. What is the circumference of the circular arc of 32° on the disc? - Percentage - fractions

About what percentage we must increase number 1/6 to get number 1/3? - Coins

Denis and Zdeno together have 97 coins. If Denis had 4 coins less than he has now, the number of the coins would be in the ratio 14: 17. Determine the number of coins owned by Denis and Zdeno. - Square roots

What is equal to the product of the square roots of 540225? - Log

Worker cut his thick log to 6 pieces for 30 min. How long he cut log to 12 pieces? - Circumscribed circle to square

Find the length of a circle circumscribing a square of side 10 cm. Compare it to the perimeter of this square. - Cylinder surface area

Volume of a cylinder whose height is equal to the radius of the base is 678.5 dm^{3.}Calculate its surface area.

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