# Examples for 8th grade - page 113

1. Dog price Tereza agreed to get a dog and 6000 crowns a year for help in a dachshund breeding station. After eight months she had to finish work and got a dog and 2000 crowns. What price does a dog have?
2. Together If 8 men, 10 women, 16 children collects ₹1024 in 4 days, how many days will be required for 6 men, 5 women and 4 boys to collect ₹768? (₹ is Indian Rupee)
3. Two gardeners The garden with an area of 81 square meters was divided by two gardeners in a ratio of 4: 5. How much did the second gardener get more first?
4. Hectoliters How deep is the pool if there are 2025 hectoliters of water and the bottom dimensions are a = 15 meters b = 7,5 meters and the water level is up to 9/10 (nine-tenths) of height.
5. 12 apples 12 apples and 2 loaves of bread cost 5.76 and 6 apples and 3 loaves of bread cost 7.68. How much is a loaf of bread?
6. Minute average In a factory, four workers are assigned to complete an order received for dispatching 1400 boxes of a particular commodity. Worker A takes 4 mins per box, Worker B takes 6 minutes per box, C takes 10 mins per box, D takes 15 mins per box. Find the average.
7. Down syndrome Down syndrome is one of the serious diseases caused by a gene mutation. Down syndrome occurs in approximately every 550-born child. Express the incidence of Down's syndrome in newborns at per mille.
8. Concentric circles There is given a circle K with a radius r = 8 cm. How large must a radius have a smaller concentric circle that divides the circle K into two parts with the same area?
9. 40% volume 40% volume with 104 uph (units per labor hour) 8 people working. What is the volume?
10. Perimeter of a rectangle If the perimeter of a rectangle is 114 meters and the length is twice the width plus 6 meters, what are the length and width?
11. Percentage increase Increase number 400 by 3.5%
12. Wave parameters Calculate the speed of a wave if the frequency is 336 Hz and the wavelength is 10 m.
13. Intersections Find the intersections of the function plot with coordinate axes: f (x): y = x + 3/5
14. Rectangle area The length of a rectangle of x units is increased by 10% and its width of y units is increased by 15%. What is the ratio of the area of the old rectangle to the area if the new rectangle?
15. Two equations Solve equations (use adding and subtracting of linear equations): -4x+11y=5 6x-11y=-5
16. Mixture 2 How many liters of water must be added to 7 liters of a 20% solution to obtain a 10% solution?
17. Taxi A taxi ride costs \$3 plus \$2.50 per mile. Write and Graph an equation in two variables that represents the total cost of a taxi ride. Alaska is the largest state in the United States and has a surface area of approximately 588,000 square miles. Montana has a surface area that is approximately 25% of the surface area of Alaska. What is the approximate surface area of Montana? Calculate circle circumference if its area is 254.34cm2 The volume of a cube is 27 cubic meters. Find the height of the cube.