# Examples for 8th grade - page 55

- The creek

Workers cleaned the creek within 3 days. The first day cleanse one-fifth the length of the creek, the next day 40% of the length of the stream and the third day 8 km length of the creek. How long is a creek? - Isosceles trapezoid

What is the height of an isosceles trapezoid, the base of which has a length of 11 cm and 8 cm and whose legs measure 2.5 cm? - Juice box 2

Box with juice has the shape of a cuboid. Internal dimensions are 15 cm, 20 cm and 32 cm. If the box stay at the smallest base juice level reaches 4 cm below the upper base. How much internal volume of the box fills juice? How many cm below the top of the - Painting

To paint the pool with dimensions: 2 meters depth, 3m x 4m we bought paint to 50 meters square. How many "paint" will be a waste? - James

James paints a fence. If every day instead of 14 planks painted 16 would be done on one day earlier. How many of planks has a fence altogether? - Number

What number is 20 % smaller than the number 198? - Saw

Blade circular saw with a diameter 42 cm turns 825 times per minute. Expresses his cutting speed in meters per minute. - Water well

Drilled well has a depth 20 meters and 0.1 meters radius. How many liters of water can fit into the well? - Sisters

Sisters Zuzka Lenka and Vierka has save for a new bike. Zuzka save € 90, Lenka save € 90 and Vierka save € 82. Missing 30% gave them their mother. What is the price of the bike? - Cleaners

Milan would clean up the room for 2.5 hours, Eric would take 10 hours. How long they swept the room together? - Surveyor

Calculate the area of what may vary rectangular, if it focused by surveyor and found the dimensions 18 x 15 m while in each of the four joint points can be position deviation 25 cm? - Average height

In a class are 34 students. The average height of students is 165 cm. What will be the average height of students in the classroom when two pupils tall 176 cm and 170 cm moved from this school/class? - Trapezium

The area of trapezium is 35cm^{2}find its altitude if the bases are 6cm and 8cm. - Circle and hexagon

Calculate the radius of a circle whose circumference is 8.4 cm longer than the circumference of the inscribed regular hexagon. - Copper plate

Calculate the thickness of the copper plate with a density 8.7 g/cm³ measuring 1.5 meters and 80 cm and its weight is 3.65 kg - Prism

Base of perpendicular triangular prism is a right triangle with cathetuses 4.5 cm and 6 cm. What is the surface of the prism, if its volume of 54 cubic centimeters. - Mother and daughter 2

The mother is 40 years older than her daughter. How old is the mother if her age is eight thirds age of daughter? - CD disc

A compact disc has a diameter of 11.8 cm. What is the surface area of the disc in square centimeters? - The ship

The ship went upstream speed of 20 km/h in relation to water. River flows at speed 10 km/h. After half an hour, he stopped and returned downstream to the starting point. How long it took way back when even if downstream speed of ship is 20 km/h in relation - Efficiency

A certain device consumes 28 kW and delivers 14 kW. Find its efficiency.

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