Examples for 8th grade - page 10
Jane on birthday brought 30 lollipops and 24 chewing gum for their friends. How many friends has, if everyone receives the same number of lollipops and chewing gums? How much chewing gum and lollipops got any friend?
Pizza with a diameter 41 cm have weight 531 g. What diameter will have a pizza weighing 749 g if it is make from the same cloth (same thickness....) and same decorated?
- Prism X
The prism with the edges of the lengths x cm, 2x cm and 3x cm has volume 48000 cm3. What is the area of surface of the prism?
- Pyramid roof
1/3 of area of the roof shaped regular tetrahedral pyramid with base edge 10 m and height of 4 m is already covered with roofing. How many square meters still needs to be covered?
The barrel is 239 litres of 31% acid. How many percent acid occurs when 88 litres revoke and replace it with the same amount of water?
Two workers fulfill a certain task when working together for 7 days, the first if he worked himself done work in 18 days. How many days will do whole job a second worker?
On the road sign, which informs the climb is 20%. Car goes 5 km along this road. What is the height difference that car went?
Video is 250% more expensive than tape recorder. How many percent is tape recorder less expensive than video?
Find the length of the other diagonal and area of rhombus. The perimeter of a rhombus is 40 cm and one of the diagonals is of length 10 cm.
- Gear wheels
Two gear wheels, which fit together have number of teeth z1=132 and z2=123. Calculate the speed of the first wheel, if the second wheel rotates 247 revolutions per minute.
- ISO triangle
Calculate the area of an isosceles triangle KLM if the length of its sides are in the ratio k:l:m = 4:4:3 and has perimeter 128 mm.
- Cylinder - basics
Cylinder with base radius r = 37 cm and height h=74 cm. Calculate:
Circular cone with height h = 11 dm and base radius r = 4 dm slice plane parallel to the base. Calculate distance of the cone vertex from this plane, if solids have the same volume.
- Climb in percentage
The height difference between points A and B is 442 m. Calculate the percentage of route climbing if the horizontal distance places A, B is 6.8 km.
- Tetrahedral pyramid
Calculate the volume and surface area of a regular tetrahedral pyramid, its height is $b cm and the length of the edges of the base is 7 cm.
From the cottage started first group of tourists at 10:00 AM at speed 4 km/h. The second started after them 39 minutes later at speed 6 km/h. How long and how many kilometers from the cottage will catch the first group?
- Hollow sphere
Calculate the weight of a hollow gold sphere (density 19.32 g/cm3), if the outer diameter is 18 cm and wall thickness is 4 mm.
- Number ratio
Calculate two positive numbers that its ratio is 4:4 and sum was 184.
How many m2 of copper plate should be to replace roof of the tower conical shape with diameter 13 m and the angle at the vertex of the axial section is 150°?
Three cubes are glued into prism, sum of the lengths of all its edges is 259 cm. What is the length of one edge of the original cube?