Examples for 8th grade - page 23
- 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?
- Bundle of candies
In the store has 168 chocolates, caramel candies 224 and 196 hard candies. How many packages we can do and how many of candies will be in each package?
- Distance runner
Distance runner already climbed three fifths of the total route. Thus passed 90 km. How many km he have to stop? How long is his route?
- Feed for horses
In the kennel have feed for two horses for 21 days. The station brought an additional 5 horses. How many days will last the feed for all the horses if they have the same daily ration?
From how many tiles 20 cm by 30 cm we can build a square of maximum dimensions, if we have maximum 390 tiles.
Convert to arc measures (radians): 1367 ° Result write as a multiple of π
- 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?
Cyclist started out of town at 20 km/h. After 0.6 hours car started behind him in the same direction and caught up with him for 52 minutes. How fast and how long went car from the city to caught cyclist?
The owner of the house is insured against natural disasters and pays 0.04% annually of the value of house 103 Eur. Calculate the value of the house. Calculate the probability of disaster, if you know that 42% of the insurance is to pay damages.
Margaret and Zdena weighs the same and Petra 3 kg more. Together weigh 156 kg. How much does they weigh?
- Classs mean
Class size is 30 students, math was not worse than sign 2. Determine the number of pupils who were sign 1 if the class had a 1.4 sign average.
- Sales off
Goods is worth € 31 and the price of goods fell two weeks in a row by 10%. How many % decreased overall?
- Ski class
Class attend 30 boys and some number of girls. Ski training was attended by 28 boys and all the girls, which was 95% of all students. How many girls attend this class? How many percent is that?
- 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.
- Barrel 3
Barrel with water has a weight 118 kg. When we get off 75% of water it has a weight 35 kg. How many kg has empty barrel?
A one-third of unknown number is equal to five times as great as the difference of the same unknown number and number 28. Determine the unknown number.
- 7 roses
Peter buys 7 roses. When he pay for it left him 4 euro. If he bought 5 roses left him 40 euros. How many euros had Peter before buying?
At the pharmacy are in one container 20% solution in the second 50% solution of disinfectant. They need to prepare 24 L of 36-percent solution. What amount of solution from each container is needed to mix?
- Quadrant II
Calculate the radius of the quadrant, which area is equal to area of circle with radius r = 15 cm.
The areas of the two circles are in the ratio 1:15. The larger circle has diameter 25. Calculate the radius of the smaller circle.