# Examples for 8th grade - page 73

- Eight palm

There grows 8 palms by the sea. At the first sitting one parrot, on second two, on third sits four parrots on each other twice the previous parrots sitting on a previous palm. How many parrots sitting on eighth palm? - Hydrochloric acid

Determine the concentration of which must have a solution of hydrochloric acid that mixing 10 l of the solution with 8 liters of 26% solution to get the solution with a concentration of 50%? - Pumps A and B

Pump A fill the tank for 12 minutes, pump B for 24 minutes. How long will take to fill the tank if he is only three minutes works A and then both pumps A and B? - Jam

Jar with jam weighs 800 grams. Jam weighs three times as much as the empty glass. What is the weight of jam that is in the glass? - Umbrella

Can umbrella 75 cm long fit into a box of fruit? The box has dimensions of 390 mm and 510 mm. - Cylinder twice

If the radius of the cylinder increases twice, and the height is reduced twice, then the volume of the cylinder increases (how many times?): - Expressions

Expression (3a-7).(3a+7) is identical with: ? - Seamstress 2

Seamstress bought two kinds of textile in whole meters. One at 50 SKK and the second 70 SKK per meter. How many meter bought from this two textiles when paid totally 1540 SKK? - Sidewalk

The city park is a circular bed of flowers with a diameter of 8 meters, around it the whole length is 1 meter wide sidewalk . What is the sidewalk area? - Unknown number 7

16% of the unknown number is by 21 less than unknown number itself. Determine the natural unknown number. - Performance

Same number of tickets sold for 15 CZK, 20 CZK, 30 CZK and 40 CZK a total of CZK 13,230 on theatre performance. How many tickets were sold for this performance? - Collecting

For the first week of material collection events are picked up at the school 850 kg of paper and 305 kg of rags which represented 55% of total collection for 14 days. How many kilograms of secondary raw materials were handed over totally? - Roof tiles

The roof has a trapezoidal shape with bases of 15 m and 10 m, height of roof is 4 meters. How many tiles will need if on 1 m^{2}should be used 8 tiles? - Prism - eq triangle

Calculate the volume and surface of the prism with the base of an equilateral triangle with side a = 4cm and the body height is 6cm. - Grass seeds

How many kg of grass seed is needed to be sowing a circular field with a diameter of 120 meters when the 1 m^{2}should be used 0.8 grams seeds? - Students

In the front row sitting three students and in every other row 11 students more than the previous row. Determine how many students are in the room when the room is 9 lines, and determine how many students are in the seventh row. - Conference

148 is the total number of employees. The conference was attended by 22 employees. How much is it in percent? - Ski tow

The ski club has 168 pupils and used lift with 60 seats, while students always follow the same sequence in filling seats. How many times while riding a ski lift skier sitting in the same seat as the first run? - Circular lawn

Around a circular lawn area is 2 m wide sidewalk. The outer edge of the sidewalk is curb whose width is 2 m. Curbstone and the inner side of the sidewalk together form a concentric circles. Calculate the area of the circular lawn and the result round to 1 - Mr. Happy

Mr. Happy planted 36.6 meters square gardens grass; It's a third of the garden more than half of the garden. What is square area of this garden?

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