# Examples for 8th grade - page 66

- Percentage and rectangle

About what percentage increases perimeter and area of a rectangle if both the sides 12 cm and 10 cm long we increase by 20%? - Railway wagon

The railway wagon holds 75 m^{3}load. Wagon can carry a maximum weight of 30 tonnes. What is the maximum density that may have material with which we could fill this whole wagon? b) what amount of peat (density 350 kg/m3) can carry 15 wagons? - Cube

Calculate the surface of the cube ABCDA'B'C'D' if the area of rectangle ACC'A' = 344 mm^{2.} - Chord distance

The circle k (S, 6 cm), calculate the chord distance from the center circle S when the length of the chord is t = 10 cm. - Sides od triangle

Sides of the triangle ABC has length 4 cm, 5 cm and 7 cm. Construct triangle A'B'C' that are similar to triangle ABC which has a circumference of 12 cm. - Rain

How many mm of water rained the roof space 75 m^{2}if the empty barrel with a radius of 8 dm and height 1.2 m filled to 75% its capacity? :-) - Tiles

How many tiles of 20 cm and 30 cm can build a square if we have a maximum 100 tiles? - Sweets

3 chocolate and 7 cakes cost 85, - CZK. 2 chocolates and 6 cakes cost 86, - CZK. How much is 5 chocolates and 9 cakes? I wonder how to get the result, but only by logic without the use of a system of equations - Diamond

Calculate the length of the two diagonals of the diamond if: a = 13 cm v = 12 cm - Trapezoid v3

The isosceles trapezoid has the angle at a firsst base 40 degrees less than the angle at second base. How large angles has this trapezoid ? - Saving

The boy has saved 50 coins € 5 and € 2. He saved € 190. How many were € 5 and how many € 2? - Parcel

parcel has a rectangular shape of a trapezoid with bases 12 m and 10 m and a height 8 m. On parcel was built object with a footprint an isosceles triangle shape with side 4 m and height three-quarters of a meter. What is the area of unbuild parcel? - Typing course

Before taking a typing course, Terrence could type 39 words per minute. By the end of the course, he was able to type 68 words per minute. Find the percent increase. - Truncated cone

A truncated cone has a base radius 40 cm and 10 cm and a height of 25 cm. Calculate its surface area and volume. - Cenda and Pepa

Cenda and Pepa went to the event. Cenda started alone. Canda started after him for 20 minutes. How long took Cenda to catch him? Cenda traveling at 15 km/h, and Pepa traveling at 25 km/h. - Car and cyclist

Cyclist started from town at speed 18 km/h. After 1 hour 30 min started the car from town and caught up with the cyclist in 50 minutes. How fast was a car? - Aquarium volume

The aquarium has a cuboid shape and dimensions a = 0.3 m, b = 0.85 m, c =? , V = ?. What volume has a body, if after dipping into the aquarium water level rises by 28 mm? - Cube diagonals

Determine the volume and surface area of the cube if you know the length of the body diagonal u = 216 cm. - Isosceles - isosceles

It is given a triangle ABC with sides /AB/ = 3 cm /BC/ = 10 cm, and the angle ABC = 120°. Draw all points X such that true that BCX triangle is an isosceles and triangle ABX is isosceles with the base AB. - New computer

New computer process a certain amount of data for 6 hours. For how many hours will process the same amount of data older computer that has a quarter lower performance?

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