Examples for 8th grade - page 40
- Cube 6
Surface area of one wall cube is 1600 cm square. How many liters of water can fit into the cube?
- Tetrahedral prism
The height of a regular tetrahedral prism is three times greater than the length of the base edge. Calculate the length of the base edge, if you know that the prism volume is 2187 cm3.
Loggers wanted to seed more than 700 and less than 800 trees. If they seed in rows of 37, left them 8 trees. If they seed in rows of 43, left the 11 trees. How many trees must seed ?
- Apples 2
How many apples were originally on the tree, if the first day fell one third, the second day quarter of the rest and on tree remained 45 apples?
- Pages of book
Lenka calculated that if every day to read 16 pages of the book, read a book a day earlier than had read only 14 pages a day. How many pages has this book?
- Tetrahedral prism
Calculate surface and volume tetrahedral prism, which has a rhomboid-shaped base, and its dimensions are: a = 12 cm, b = 7 cm, ha = 6 cm and prism height h = 10 cm.
- Colour - billboard
Shelftalker has the shape of a parallelogram. Its length is 4.9 m and the corresponding height is 3.5 meters. Calculate how much (kg) paint must purchase to redecoration if 1 kg cover 4 m2 of shelftalker surface.
Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm.
- Mom and daughter
Mother is 39 years old. Her daughter is 15 years. For many years will mother be four times older than the daughter?
- Supplementary angles
One of the supplementary angles are three times larger than the other. What size is larger of supplementary angles?
- Box of chocolates
In a box of chocolates was 16 candies. Christopher and Luke they were distributed: a) Christopher had about 4 candies over Luke, b) Christopher had about 6 candies less than Luke, c) Christopher had 3 times more sweet than Luke. How many had each boy can
- Pool 2
The first supply by the pool fill for five hours and the second fill for six hours, drain should be drained for 15 hours. For how many hours the pool is full, when we open both inlet now and outlet open two hours later?
- RT 11
Calculate the area of right tirangle if its perimeter is p = 46 m and one cathethus is 18 m long.
Calculate the slope of a line that intersects points (38,-23) and (-93,5).
- CD disc
A compact disc has a diameter of 11.8 cm. What is the surface area of the disc in square centimeters?
If the endpoints of a diameter of a circle are A(10, -5) and B (8, 7), what is the radius of the circle?
From wooden block carpenter cut off a small cuboid block with half the edge length. How many percent of wood he cut off?
24-member group of divers carries the air for 11 hours of diving. 4 members of the expedition sick or wasn't came. How many hours is sufficient air to other divers?
The first racer run at a speed 12 m/s and is 470 meters before the finish and ahead 22 meters before second competitor. At what speed must run the second racer to catch first racer at the finish line?
I have homework. The cube has an edge 11 cm long and I must find wall and body diagonal.