# Examples for 8th grade - page 80

- Roof 8

How many liters of air are under the roof of tower which has the shape of a regular six-sided pyramid with a 3,6-meter-long bottom edge and a 2,5-meter height? Calculate the supporting columns occupy about 7% of the volume under the roof. - Hypotenuse

Calculate the length of the hypotenuse of a right triangle with a cathetuses 71 cm and 49 cm long. - Cuboid enlargement

By how many percent increases the volume of cuboid if its every dimension increases by 30%? - Masons

1 mason casts 30.8 meters square in 8 hours. How long casts 4 masons 178 meters square? - Cuboid easy

The cuboid has the dimensions a = 12 cm, b = 9 cm, c = 36 cm. Calculate the length of the body diagonal of the cuboid. - Body diagonal

Find the cube surface if its body diagonal has a size of 6 cm. - Water reservoir

The reservoir shape of a cylinder having a diameter 8 m and a height 2.8 m. The device indicates that the reservoir contains 800 hectoliters of water. Calculate how much % of volume is used. - Remuneration

Total remuneration for workers is 47 000 CZK. The second worker received 20% more than the first and third 4000 CZK less than a second employee. How many CZK each received? - Brick wall

Garden 70 m long and 48 m wide should surround with wall 2.1 meters high and 30 cm thick. How many we will need bricks if to 1 m³ is needed approximately 300 bricks? - Cat

One-fifth of the monthly pocket money contributes Maros for food for his cat, half of the rest postpone for a new smartphone. The remaining € 8 spend. How much pocket money gets Maros a month? - Two circles

Two circles with a radius 4 cm and 3 cm have a center distance 0.5cm. How many common points have these circles? - Four friends

Four friends shared the money. Vasek got 1/4 of the total amount. Tonda received 1/3 of the rest of the money, Joe got a half from the second residue and Jirka left 80. How much money get together? - Krkonose CZ

Tourist's rod on the tourist route in the Krkonose was 1/5 of its length into the ground. Snow fell in winter and 1/3 of the length of the rod remained above the snow. Find the height of the snow if the length of the part above the snow is 32 cm greater t - Journey to school

On the way to school I went steady step. In the first half of the journey, I counted every second step, in the second half every third. How many steps I do when I went to school if I counted double step are 250 more than three steps? - Two ages

Gabrielle is 9 years younger than Mikhail. The sum of their ages is 87. What is Mikhail's age? - Profitability

The purchase price of goods is 13000, the sales price is the 20000. What is the profitability as a percentage? - Diagonals of diamond

Find the area and circumference of the diamond ABCD with 15m and 11m diagonals. - Bags

The first bag has a weight of 18 kg, the second bag is a one-third lighter than the first and the third bag has three times less the weight of all three bags together. Determine their weights. - Failure

Drivers of passenger cars have calculated that at a speed of 60 km/h arrives at destination within 40 minutes. After 20 km refrain five minutes due a technical failure. How fast must go the rest of the way to the finish came at the scheduled time? - Sum of three numbers

The sum of three numbers from which second number is 20% smaller than the first number and the third number is 25% smaller than the second number is 96. Determine this numbers.

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