# Examples for 8th grade - page 46

- Five tractors

Five tractors plow field in 4.8 hours. How long plow this field if after 1.5 hours of work two tractors went to a different field? - Parcel

Both dimensions of the rectangular parcel were increased by 26%. By how many % has increased its acreage? - Round table tablecloth

Round table has area 50.24 dm^{2}. Calculate the diameter of the circular tablecloth, if it is extend beyond the edge of the table by 30 cm. - RT 10

Area of right triangle is 84 cm^{2}and one of its cathethus is a=10 cm. Calculate perimeter of the triangle ABC. - Silo

Outer perimeter of silo is 32 m. Concrete wall is 35 cm thick. What is diameter and area of inside floor of silo? - Two pumps

The first pump fills the tank in 24 hours second pump in another 40 hours. For how long will take fill the tank if operate both pumps at the same time? - Tractor wheels

Smaller tractor wheel has a circumference of 3 meters, bigger 4 meters. On what path executes smaller wheel 6 turns over more bigger? - Salary increase

Ms. Merry salary increased by 15% and that was 83e. What should pay before the increase? - Beer permille

In the 5 kg of blood of adult human after three 10° beers consumed shortly after another is 6.6 g of the alcohol. How much is it as per mille? - Brackets

Place one pair of brackets in expression 20-16 + 10 - 4 - 2 so that the result will be 0. - Every day 7 pages

Adelka reads the book every day 7 pages. When she reads one more page a day she will read it three days earlier. How long will Adelka read a book? How much does a book of pages have? - Container with water

The weight of a container with water is 2.48 kg. If the cast 75% water, the container with water has a weight of 0.98 kg. Determine the weight of the empty container. How much water was originally in the container? - Bathroom

How many CZK we pay for lining the perimeter walls of the bathroom with rectangular shape with dimensions 3.5 m and 4 m, high 1.5 m if 1 square m tile cost 300 CZK? - Chess

How many different ways can initiate a game of chess (first pass)? - Water in aquarium

The aquarium cuboid shape with a length of 25 cm and a width of 30 cm is 9 liters of water. Calculate the areas which are wetted with water. - Hexagonal pyramid

Regular hexagonal pyramid has dimensions: length edge of the base a = 1.8 dm and the height of the pyramid = 2.4 dm. Calculate the surface area and volume of a pyramid. - Pumps

First pump flows 16 liters per second into the basin by the second pump 75% of the first and by third pump half more than the second. How long will take fill basin by all three pumps simultaneously volume 15 m^{3}(cubic meters)? - A three-digit numbers

Determine the total number of positive three-digit numbers that contain a digit 6. - Pyramid in cube

In a cube with edge 12 dm long we have inscribed pyramid with the apex at the center of the upper wall of the cube. Calculate the volume and surface area of the pyramid. - Plums

In the bag was to total 136 plums. Igor took 3 plums and Mary took 4/7 from the rest. How many plums remained in the bag?

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