# Examples for 8th grade - page 64

1. Rectangle
Perimeter of rectangle is 48 cm. Calculate its dimensions if they are in the ratio 5:3 (width:height)
2. 7 roses
Peter buys 7 roses. When he pay for it left him 4 euro. If he bought 5 roses left him 40 euros. How many euros had Peter before buying?
3. Three numbers
Find three numbers so that the second number is 4 times greater than the first and the third is lower by 5 than the second number. Their sum is 67.
4. Sea water
One tonne of sea water contains 25 kg of salt. How many tonnes of sea water need to be evaporated to obtain 1 tonne of salt?
5. Sides od triangle
Sides of the triangle ABC has length 4 cm, 5 cm and 7 cm. Construct triangle A'B'C' that are similar to triangle ABC which has a circumference of 12 cm.
6. Diagonal - simple
Calculate the length of the diagonal of a rectangle with dimensions 5 cm and 12 cm.
7. Cube diagonals
Determine the volume and surface area of the cube if you know the length of the body diagonal u = 216 cm.
8. Trip
On the trip drank 3/10 of pupils tea, 2/5 cola, 1/4 mineral water and remaining 3 juice. How many students were on the trip?
9. New computer
New computer process a certain amount of data for 6 hours. For how many hours will process the same amount of data older computer that has a quarter lower performance?
10. Grandmother
Grandmother wants to give the candies to grandchildren that when she gives 5 candy everyone 3 missing and when she gives 4 candies 3 is surplus. How many grandchildren has grandmother and how many candies has?
11. Mrs XY
Mrs Novak is employed. In January 2015 the gross income reached € 1348. Insurance is a 323.52 euros, and income taz 153.67 euros. Employer precipitated Mrs. Novak in recent clashes € 115, of which 57 euro for the savings account, and 58 euros for repayment
12. Three days
During the three days sold in stationery 1490 workbooks. The first day sold about workbooks more than third day. The second day 190 workbooks sold less than third day. How many workbooks sold during each day?
13. Sinus
Determine the smallest integer p for which the equation 4 sin x = p has no solution.
14. Apprentice
Worker and apprentice execute the work for 6 hours. Worker performs himself in 10 hours. How long do the work of an apprentice?
15. Coffee shop
To the coffee shop brought 2 types of coffee totally 50 kg. The first type was CZK 220 per kilogram, coffee second type 300 CZK per 1 kg. For all the coffee trader earned CZK 12,000. How many kilograms of coffee of first type and how many kilograms of cof
16. Cube 6
Surface area of one wall cube is 1600 cm square. How many liters of water can fit into the cube?
17. Square garden
On the plan with a scale of 1:1500 is drawn as a square garden with area 81 cm2. How many meters is long garden fence? Determine the actual acreage gardens.
18. After 16 years
After 16 years will Dana be five times older as she was four years ago. After how many years will Dana celebrate her 16th birthday?
19. Borrowed book
Jane must as soon as possible return a borrowed book. She figured that when she read 15 pages a day return book in time. Then she read 18 pages a day and then return the book one day before. How many pages should have a book?
20. Painters 4
One painter will do the job for 12 days. After a 4 1/3 day he comes second to help him and complete work together for 8 days. How long would work the second painter himself?

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