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?
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: ?
Five painters painting the fence for eight days. How many days over will take work if paint the fence only four decorators?
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 cm2 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×?
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 cm2. Determine the area of the trapezoid A
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?
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/m3.
- Daily average
Calculate the average temperature during the day, when 14 hours was 20 °C and 10 hours was 15 °C.
It is true (prove it) that if a> b> 0: ?