# Examples for 8th grade - page 77

1. Trees - orchard The 3/5 trees are apple trees and 1/3 of the trees are cherries. The remaining 5 trees are pear trees. How many trees are in the orchard.
2. Family Mom is 39 years old. Karl is eight years and Paul 4 years. For many years mother would old just like two children together?
3. Cruise liner Cruise liner runs along the river between points A and B. The journey downstream takes 40 minutes 1 hour upriver. The flow rate of the river is 3 km/h. What is the speed of cruise liner?
4. Resistance Determine the resistance of the bulb with current 200 mA and is in regular lamp (230V).
5. Cableway Cableway has a length of 1800 m. The horizontal distance between the upper and lower cable car station is 1600 m. Calculate how much meters altitude is higher upper station than the base station.
6. Image scale The actual image dimensions are 60 cm x 80cm and has a reduced size 3 cm x 4 cm. At what scale the image was reduced?
7. TVs Production of television sets increased from 3,500 units to 4,200 units. Calculate the percentage of production increase.
8. Family parcels In father will he divided the land so that the older son had three bigger part than younger son. Later elder son gave 2.5 ha field to younger and they had both the same. Determine the area of family parcel.
9. Pyramid Z8–I–6 Each brick of pyramid contains one number. Whenever possible, the number in each brick is lowest common multiple of two numbers of bricks lying directly above it. That number may be in the lowest brick? Determine all possibilities.
10. Diagonals of diamond Find the area and circumference of the diamond ABCD with 15m and 11m diagonals.
11. Shell of cylinder Calculate the content of shell the 1.6 m height cylinder with a base radius of 0.4 m.
12. Isosceles trapezoid Calculate the circumference and the contents of the isosceles trapezoid if you know the size of the bases is 8 and 12 cm and the size of the arms is 5 cm.
13. Cost reduction Two MP3 players whose price was equal to originally have been discounted the first by 20%, the second by 35%. After the price reduction was the difference in their prices 750, - CZK. What was the original price of each of the two players?
14. Two numbers The sum of the two numbers is 1. Find both numbers if you know that half of the first is equal to one seventh of the second number.
15. Is right triangle Decide if the triangle XYZ is rectangular: x = 4 m, y = 6 m, z = 4 m
16. Fuel mileage You have 3/8 tank of fuel. Estimate fuel consumption @ 6mpg. Estimate speed @ 50mph. Your fuel tank holds 200 gals. Figure out fuel mileage.
17. Rabbits 3 Viju has 40 chickens and rabbits. If in all there are 90 legs. How many rabbits are there with Viju?
18. Brick wall Garden 70 m long and 48 m wide should surround with wall 2.1 meters high and 30 cm thick. Wall will be built on the garden ground. How many will we need bricks if to 1 m³ is required approximately 300 bricks?
19. Right triangle ABC Calculate the perimeter and area of a right triangle ABC, if you know the length of legs 4 cm 5.5 cm and 6.8 cm is hypotenuse.
20. Percentages Calculate the percentages to two decimal places: a / 15 min in 4 hours B / 35 cm2 of 12.5 dm2 c / 2dm2 of 400 cm2 D / 0.2 liters from 2.2 liters

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