Examples for 8th grade - page 57
Jožko with Fero painted the bench for four hours. How many hours would take work if four friends help him?
- Uranium ore
Uranium ore contains 0.2% of pure uranium and pure uranium contains 0.07% of fissile uranium. How many grams of fissile uranium contains 2200 ton of uranium ore?
Calculate the sides of the triangle if its area S = 630 and the second cathethus is shorter by 17.
- 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.
Both dimensions of the rectangular parcel were increased by 40%. By how many % has increased its acreage?
- Family and age ratios
Age of father and son are in the ratio 10:3; age of father and daughter are in the ratio 5:2. How old is father and son, if daughter is 20 years old? In what ratio is age sister and brother?
The perimeter of the parallelogram is 202 cm. The length of one side is 1.2-times longer than the length of the shorter side. What is the length of sides of a parallelogram?
In the square ABCD point P is in the middle of the DC side and point Q in the middle pages AD. If the area of quadrilateral BQPC is 96 cm2, what is the area of ABCD?
- Sales off
Calculate what was the original price of the good, if the price after discount 40% and the subsequent rise of 30% is 4000 USD.
Rhombus has side 23 cm and and one of diagonal 36 cm long. Calculate its area.
- Trapezoid ABCD v2
Trapezoid ABCD has length of bases in ratio 3:2. The area of riangle ACD is 956 dm2. What is the area of trapezoid ABCD?
- TV commercials
For the typical one-hour prime-time television slot, the number of minutes of commercials is 7/23 of the minutes of the actual program. Determine how many minutes of the program are shown in that one hour.
- Round table
Round table with diameter d = 95 cm is coated by square tablecloth with a side length 122 cm. About how many cm is higher center of tablecloth than its cornes?
- Slope of the pool
Calculate slope (rise:run) of the bottom of swimming pool long 40 m. Water depth at beginning of pool is 1.15 m (for children) and depth at end is 1.92 m (for swimmers). Slope express as percentage and as angle in degrees.
- Rectangles - sides
One side of the rectangle is 25 cm longer than second. Shortens longer side by 14 cm and extend shorter by 13 cm increases the area of the rectangle by 130 cm2. What are the dimensions of the original rectangle?
- Similarity coefficient
The ratio of similarity of two equilateral triangles is 3.9 (ie 39:10). The length of the side of smaller triangle is 3 cm. Calculate the perimeter and area of the larger triangle.
Calculate the volume of a cuboid ABCDEFGH if |AB| = 11 cm, |BC| = 8 cm and the angle ∠CDG = 29.4°
- SAS triangle
The triangle has two sides long 7 and 19 and included angle 144°11'59″. Calculate area of this triangle.
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.
- Negative percentage
In 2003, the company had a loss of 25600 Euros. Two years later he was already in profit 25200 Eur. Calculate what percentage of the company increased profits in this two years.