# Examples for 8th grade - page 80

- Lawns

Before a sports hall are two equally large rectangular lawns, each measuring 40 m and 12 m. Maintenance of 10m² lawn cost 45 CZK yearly. On each lawn is circular flowerbed with a diameter 8 meters. How much money is needed each year to take on lawn care?. - Tree shadow 3

A 2-meter rod casts a shadow 3.2 m long. How high is a tree with a shadow of 14.4 m ? - Earth and Sun

Earth is 150 million km away from the Sun, 300,000 km of sunlight travels in 1 second. How long will the light come from the Sun to the Earth? - Three-digit

How many three-digit natural numbers do not have the number 7? - Bags

The first bag has a weight of 18 kg, the second bag is a one-third lighter than the first and the third bag has three times less the weight of all three bags together. Determine their weights. - Hypotenuse

Calculate the length of the hypotenuse of a right triangle with a cathetuses 71 cm and 49 cm long. - Cuboid enlargement

By how many percent increases the volume of cuboid if its every dimension increases by 30%? - Cars 6

At 9:00 am two cars started from the same town and traveled at a rate of 35 miles per hour and the other car traveled at a rate of 40 miles per hour. After how many hours will the cars be 30 miles apart? - Divisible by 5

How many three-digit odd numbers divisible by 5, which are in place ten's number 3? - Working together

One painter paint the nursery in 10 days, the second in 8 days. How many days will the nursery be painted if they work together? - Water reservoir

The reservoir shape of a cylinder having a diameter 8 m and a height 2.8 m. The device indicates that the reservoir contains 800 hectoliters of water. Calculate how much % of volume is used. - Scale 3

Miriam room is 3.2 meters wide. It is draw by line segment length 6.4 cm on floor plan. In what scale it is plan of the room? - Equation

? - Angles in ratio

The size of the angles of the triangle are in ratio x: y = 7: 5 and the angle z is 42° lower than the angle y. Find size of the angles x, y, z. - Body diagonal

Find the cube surface if its body diagonal has a size of 6 cm. - Four friends

Four friends shared the money. Vasek got 1/4 of the total amount. Tonda received 1/3 of the rest of the money, Joe got a half from the second residue and Jirka left 80. How much money get together? - Factory

In the factory workers work in three shifts. In the first inning operates half of all employees in the second inning and a third in the third inning 200 employees. How many employees work at the factory? - Remuneration

Total remuneration for workers is 47 000 CZK. The second worker received 20% more than the first and third 4000 CZK less than a second employee. How many CZK each received? - Reciprocal equation

Determine the root of the equation: 9/x-7/x=1 - Masons

1 mason casts 30.8 meters square in 8 hours. How long casts 4 masons 178 meters square?

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