# Examples for 8th grade - page 18

- Coin and die

Flip a coin and then roll a six-sided die. How many possible combinations are there? - Pumps

Pump that draws water at velocity 3.5 liters per second water from a construction trench take 35 minutes. a) Find out how many minutes the water would run out of the trench pump that draws 7.4 liters of water per second. b) What is the pumping velocity wo - Hollow sphere

Steel hollow sphere floats on the water plunged into half its volume. Determine the outer radius of the sphere and wall thickness, if you know that the weight of the sphere is 0.5 kg and density of steel is 7850 kg/m^{3} - Christmas Day

In leap years was 53 Sundays. On what day of the week fell to Christmas Day? - Slope of the pool

Calculate slope (rise:run) of the bottom of swimming pool long 40 m. Water depth at beginning of pool is 1.15 m (for children) and depth at end is 1.92 m (for swimmers). Slope express as percentage and as angle in degrees. - 3y inflation

Price of the medicament rise in the first year by 8%, the second year fell by 4% and in the third year increased by 10%. Calculate the average annual increase in price of the medicament. - Road

Average climb of the road is given by ratio 1:29. By what angle road average climb? - Mystery of stereometrie

Two regular tetrahedrons have surfaces 56 cm^{2}and 126 cm^{2.}In what ratio is their volumes? Write as a fraction and as a decimal rounded to 4 decimal places. - Divisibility

Determine the smallest integer which divided 8 gives remainder 6 when divided 19 gives remainder 9 and when divided by 11 gives remainder 2. - Hexagonal pyramid

Calculate the volume and the surface of a regular hexagonal pyramid with a base edge length 3 cm and a height 5 cm. - Drunk man

Drunkman has 2.1‰ of alcohol in the blood. How many grams of alcohol has in blood, if he have 6 kg of blood? - Lid

What is the weight of concrete cover (lid) to round shape well with a diameter 1.3 m, if the thickness of the cover is 15 cm? 1 m^{3}of concrete weighs 2190 kg. - Sea

How far can you see from the ship's mast, whose peak is at 11 meters above sea level? (Earth's radius is 6370 km). - Electronics: Resistors in parallel

From relation for calculating the resistance of parallel combination of resistors: ? Calculate the R, if R_{1}= 8kΩ a R_{2}= 18kΩ - Purchase

Mother bought 5 boxes of milk and 7 kg of potatoes and paid a total CZK 147. Aunt bought 7 boxes of milk and 3 kg of potatoes and paid 131 CZK. What is the price of one carton of milk and 1 kg of potatoes? How CZK together would have saved if bought at the - Lines

Five bus lines runs at intervals 3, 5, 10, 11, 13 minutes. In the morning, suddenly start at 7:00. After how many minutes the bus lines meet again? - Nine-gon

Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm. - Elevation

What must be the elevation of an observer in order that he may be able to see an object on the earth 814 km away? Assume the earth to be a smooth sphere with radius 6378.1 km. - Pit

Pit has shape of a truncated pyramid with rectangular bases and is 2.8 m deep. The length and width of the pit is the top 3 × 1.5 m bottom 1 m × 0.5 m. To paint one square meter of pit we use 0.3 l of green colour. How many liters of paint is needed when w - AVG of INT

What is the average of the integers from 7 throuht 15 inclusive?

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