# Examples for 8th grade - page 72

- Roof tiles

The roof has a trapezoidal shape with bases of 15 m and 10 m, height of roof is 4 meters. How many tiles will need if on 1 m^{2}should be used 8 tiles? - Unknown number 7

16% of the unknown number is by 21 less than unknown number itself. Determine the natural unknown number. - Sidewalk

The city park is a circular bed of flowers with a diameter of 8 meters, around it the whole length is 1 meter wide sidewalk . What is the sidewalk area? - Ski tow

The ski club has 168 pupils and used lift with 60 seats, while students always follow the same sequence in filling seats. How many times while riding a ski lift skier sitting in the same seat as the first run? - Students

In the front row sitting three students and in every other row 11 students more than the previous row. Determine how many students are in the room when the room is 9 lines, and determine how many students are in the seventh row. - Prism - eq triangle

Calculate the volume and surface of the prism with the base of an equilateral triangle with side a = 4cm and the body height is 6cm. - Mr. Happy

Mr. Happy planted 36.6 meters square gardens grass; It's a third of the garden more than half of the garden. What is square area of this garden? - Sales stores

The first sales store passed the 1/3 and the second 2/5 of the total amount of goods.In third store passed the 2/3 rest of the goods. The remaining 40 kg of goods put into fourth store. How many kilograms of goods pass to a third store? - Mr and Mrs

Mr. Calda and Mrs. Cald have a total of 139 years. How many years have when we know that Mr. Calda is 9 years older than Mrs. Cald - Conference

148 is the total number of employees. The conference was attended by 22 employees. How much is it in percent? - Circular lawn

Around a circular lawn area is 2 m wide sidewalk. The outer edge of the sidewalk is curb whose width is 2 m. Curbstone and the inner side of the sidewalk together form a concentric circles. Calculate the area of the circular lawn and the result round to 1 - Triangle angles

In a triangle ABC the interior angle at the vertex C is twice as the internal angle at the point A. Outer angle at the point B measured 117 degrees. How big is the outer angle at the vertex A? - Parking

120 vehicles parking on the morning. Pasenger car is charged 20 CZK, 50 CZK per bus. The guard collected for parking 2640 CZK in total. How many cars and how many buses stood in the parking? - Pears

Andrew, Lenka and Rasto have together 232 pears. Lenka has 28 more than Rasto and Rasto pears have 96 more than Andrew. Determine how much each of them has pears. - Skiing meeting

On the skiing meeting came four friends from 4 world directions and led the next interview. Charles: "I did not come from the north or from the south." Mojmir "But I came from the south." Joseph: "I came from the north." Zdeno: "I come from the south." W - 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? - Billboard

Rectangular billboard is 2.5 m long with a diagonal 2.8 m long. Calculate the perimeter and the content area of the billboard. - One-third

A one-third of unknown number is equal to five times as great as the difference of the same unknown number and number 28. Determine the unknown number. - Pipe cross section

The pipe has an outside diameter 1100 mm and the pipe wall is 100 mm thick. Calculate the cross section of this pipe. - Class pairs

In a class of 34 students, including 14 boys and 20 girls. How many couples (heterosexual, boy-girl) we can create? By what formula?

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