# Examples for 8th grade - page 37

1. Pedestrian and the cyclist
Pedestrian and cyclist went against each from the two cities that are distant 40 km. Pedestrian started 30 minutes before the cyclist and walk an average speed of 5 km/h. What speed went cyclist when met after 120 minutes from the start of the pedestrian?
2. Square
If we increase one side of square by its one-half then square perimeter increase by 10 cm. What is the side of the square?
3. Conserving water
Calculate how many euros are spent annually on unnecessary domestic hot water, which cools during the night in pipeline. Residential house has 129 m of hot water pipelines 5/8" and the hot water has a price of 7 Eur/m3.
4. Scale
Cylinder was drawn in scale 2:1. How many times is the volume of the cylinder smaller in reality?
5. Peleton
Cycling race was run at an average speed of 45 km/h. One cyclist lost with defect 8 minutes. How long and how far he must go at speed 51 km/h to catch peleton again?
6. Drunk and alcohol
One drunk measured 2.7 ‰ alcohol in the blood, another 1.75 ‰. How many grams of alcohol in the blood they had if they has 6 kg of blood?
7. Sports games
Pupils of same school participated district sports games. When dividing into teams found that in the case of the creation teams with 4 pupils remaining 1 pupil, in the case of a five-member teams remaining 2 pupils and in the case of six-members teams r
8. Tin with oil
Tin with oil has the shape of a rotating cylinder whose height is equal to the diameter of its base. Canned surface is 1884 cm2. Calculate how many liters of oil is in the tin.
9. Simple interest
Peter put into bank 790 euros deposit. After 2 years on account overall was 974 euro. What was the interest rate if bank add simple interest?
10. Climb
For horizontal distance 4.9 km road rise by 6.1 m. Calculate the road pitch in ‰ (permille, parts per thousand).
11. Car rent
Rental cars are paid a fixed daily fee plus 16 cents for each kilometer traveled. Samuel want to rent a car for a day and worked out that will pay 175 euros. When paying he got a 20% discount on the daily fee, the cost per kilometer is unchanged. Samuel th
12. Square and circle
Into square is inscribed circle with diameter 10 cm.What is difference between circumference square and circle?
13. Annulus
Two concentric circles form an annulus of width 10 cm. The radius of the smaller circle is 20 cm. Calculate the content area of annulus.
14. Solution
In 469 dl red solution is 84 dl red color and in 102 dl blue solution is 52 dl blue color. How many dl of red and blue dl color solution must be mixed to get a mixture of 247 dl contain 116 dl of color?
15. Rhombus IV
Calculate the length of the diagonals of the rhombus, whose lengths are in the ratio 1: 2 and a rhombus side is 35 cm.
16. Louvers
The company charges for office equipment louvers total 262 Eur. From the delivery bill is obvious that the louvers are 76 Eur expensive than their installation. What percentage of the total charged is the installation of louvers?
17. Father and son
Father is 48 years old, son 23. When will be the father twice older than a son?
18. Logs
The log has diameter 30 cm. What's largest beam with a rectangular cross-section can carve from it?
19. Bus stop
Determine at what time the bus leaves from the bus stop outside the village, if you know that when you leave home at 8:00 and go at speed 3 km/h, you come to a stop 9 minutes after the departure of the bus, and when you go speed at 4 km/h, you come to the
20. Raffle
In the pool is numbers from 1 to 115. What is the probability that a randomly selected number is not a prime number?

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