# Examples for 8th grade - page 79

1. 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?
2. Hypotenuse Calculate the length of the hypotenuse of a right triangle with a catheti 71 cm and 49 cm long.
3. 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.
4. Cuboid enlargement By how many percent increases the volume of cuboid if its every dimension increases by 30%?
5. 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?
6. 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?
7. 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.
8. Divisible by 5 How many three-digit odd numbers divisible by 5, which are in place ten's number 3?
9. 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?
10. Equation ?
11. 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.
12. 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?
13. Body diagonal Find the cube surface if its body diagonal has a size of 6 cm. Find the volume and surface of a regular quadrilateral pyramid if the bottom edge is 45 cm long and the pyramid height is 7 cm.
15. Reciprocal equation Determine the root of the equation: 9/x-7/x=1
16. Conva How many liters of water fit into the shape of a cylinder with a bottom diameter 20 cm and a height 45 cm?
17. Potatoes 6 The farmer brought potatoes to the market. In the first hour he sold two-fifths of the potatoes brought, in the second hour he sold five-sixth of the remaining potatoes, and in the third hour he had sold the last 40kg of potatoes. How many kg of potatoes d
18. Garden The garden has a rectangular shape with lengths of 25 and 40 meters. It has been expanded so that each of its size increased by one fifth. How many square meters increased its acreage?
19. Masons 1 mason casts 30.8 meters square in 8 hours. How long casts 4 masons 178 meters square? The ladder is 10 m long The ladder is 8 m high How many meters is the distant heel from the wall?