# Examples for 8th grade - page 36

1. Unknown number Samuel wrote unknown number. Then he had add 200000 to the number and the result multiply by three. When it calculated he was surprised, because the result would have received anyway, if write digit to the end of original number. Find unknown number.
2. Cylinder - h2 Cylinder volume is 2.6 liters. Base area is 1.3 dm2. Calculate the height of the cylinder.
3. 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?
4. 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?
5. 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.
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. 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.
8. Scale Cylinder was drawn in scale 2:1. How many times is the volume of the cylinder smaller in reality?
9. Climb For horizontal distance 4.2 km road rise by 6.3 m. Calculate the road pitch in ‰ (permille, parts per thousand).
10. 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?
11. 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?
12. 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.
13. 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
14. Square and circle Into square is inscribed circle with diameter 10 cm.What is difference between circumference square and circle?
15. 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
16. 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?
17. 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.
18. Painting rooms If Dano paint three hours daily given work he complete in 7.5 days. How many hours a day would have to work to finish the job 1.5 days earlier?
19. 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?
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?

Do you have an interesting mathematical word problem that you can't solve it? Enter it, and we can try to solve it.

To this e-mail address, we will reply solution; solved examples are also published here. Please enter the e-mail correctly and check whether you don't have a full mailbox.

Please do not submit problems from current active competitions such as Mathematical Olympiad, correspondence seminars etc...