# Examples for 8th grade - page 8

- Two tributaries

Two tributaries of the pool fill it in 10 hours. One of the tributaries would fill 15 hours. How long would fill the first tributary? - Friends in cinema

5 friends went to the cinema. How many possible ways can sit in a row, if one of them wants to sit in the middle and the remaining's place does not matter? - Lorry

The lorry was loaded with 27 boxes of 24 kg. How many boxes with weight 36 kg can be loaded, if total load must be same? - Similarity of squares

The ratio of the similarity of the squares ABCD and KLMN is 2.5. Square KLMN area is greater than area of a square ABCD with side a: ? - Painters

Five painters painting the fence for eight days. How many days over will take work if paint the fence only four decorators? - Estate

Semicircle estate must be fence. The straight section has 44 meters long fence. How many meters of fence should buy? - Square grid

Square grid consists of a square with sides of length 1 cm. Draw in it at least three different patterns such that each had a content of 6 cm^{2}and circumference 12 cm and that their sides is in square grid. - Lie/do not lie

The function is given by the rule f(x) = -x-12. Determine whether point D[-4; 2] lies on this function. Solve graphically or numerically and give reasons for the your answer. - No. of divisors

How many different divisors has number ?? - Sphere growth

How many times grow volume of sphere if radius rises 3×? - Division

Three siblings Helena, Oliver and George split the bag with candies on merit in the ratio 1:6:3. How many candies should each get if in bag were 210? - Square and circles

Square with sides 41 m is circumscribed and inscribed with circles. Determine the radiuses of both circles. - Trapezoid MO-5-Z8

ABCD is a trapezoid that lime segment CE divided into a triangle and parallelogram as shown. Point F is the midpoint of CE, DF line passes through the center of the segment BE and the area of the triangle CDE is 3 cm^{2.}Determine the area of the trapezoid A - Pentagon

Within a regular pentagon ABCDE point P is such that the triangle is equilateral ABP. How big is the angle BCP? Make a sketch. - Parquet floor

Three workers laid parquet floor for 1.957 hour. The first one would do this work alone 5 hours, the second in 9 hours. For how many hours would fulfill this work the third worker, if he worked alone? - Intersections

How many intersections have circles with radius 12 dm and 17 dm, if the distance of their centers is 20 dm. - Rhombus HP

Calculate area of the rhombus with height 98 mm and perimeter 20 mm. - Air mass

What is the weight of the air in a classroom with dimensions 5 m × 2 m × 3.1 m ? The air density is 1.293 kg/m^{3.} - Daily average

Calculate the average temperature during the day, when 14 hours was 20 °C and 10 hours was 15 °C. - Reciprocal

It is true (prove it) that if a> b> 0: ?

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