Examples for 8th grade - page 23
Janitor tosses 26 cm layer of snow on the school grounds for 90 minutes. How many friends would have to call for help if snow needs to have bowled for 15 minutes. We assume that at the same time bow all the same amount of snow.
- Angles ratio
In a triangle ABC true relationship c is less than b and b is less than a. Internal angles of the triangle are in the ratio 5:4:9. The size of the internal angle beta is:
- Three friends
The three friends spent 600 KC in a teahouse. Thomas paid twice as much as Paul. Paul a half less than Zdeněk. How many each paid?
- Chicken and rabbits (classic)
Grandmother breeding chickens and rabbits. It found that the yard has 22 heads and 66 legs. How many chickens and rabbits breeding in the yard?
Perimeter of regular hexagon is 41. Calculate its circumradius (radius of circumscribed circle).
How many different ways can sit 5 boys and 5 girls in line, if girls want to sit on the edge?
From the observatory 15 m high and 39 m from the river bank, river width appears in the visual angle φ = 22°. Calculate width of the river.
- Short cut
Imagine that you are going to the friend. That path has a length 330 meters. Then turn doprava and go another 840 meters and you are at a friend's. The question is how much the journey will be shorter if you go direct across the field?
- Diofant equation
In the set of integers (Z) solve the equation: ? Write result with integer parameter ? (parameter t = ...-2,-1,0,1,2,3... if equation has infinitely many solutions)
John has collected half a bucket of raspberries in 45 minutes, Eva collects the whole bucket in an hour. How many minutes it would take to fill a bucket if the two children work together?
In the dining room at one table sit Thomas, Filip and Martin. Together they eat 36 donuts. How many donuts eaten everyone, when Filip ate twice as much as Thomas and Martin even half over Filip?
- Triangular prism
Calculate the surface area and volume of a triangular prism, base right triangle if a = 3 cm, b = 4 cm, c = 5 cm and height of prism h=12 cm.
- Floating floor
In the new building is considered a floating floor worker in each room. 30 minutes lay 9 m2 of the floor. How long 3 workers laid the floor in 4 rooms with a total area of 90 m2?
- Three digits number 2
Find the number of all three-digit positive integers that can be put together from digits 1,2,3,4 and which are subject to the same time has the following conditions: on one positions is one of the numbers 1,3,4, on the place of hundreds 4 or 2.
Sum of interiol angles of 9-gon is:
- Hockey players
After we cycle five hockey players sit down. What is the probability that the two best scorers of this crew will sit next to each other?
- Price reduction
Price of camera is 800 USD on sale its price reduced to 423 USD. Calculate the percentage reduction in the price of the camera.
Five pumps pumped 1,800 hl of water for 3 hours. How many hectoliters of water pump same two powerful pumps for six hours?
- Runner 2
Marian run 12 meters in 8 seconds. How far would Marian run for 70 seconds, if still run at the same pace?
- 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?