Examples for 8th grade - page 52
- Waiting room
In the waiting room are people and flies. Together they have 15 heads and 50 legs (fly has 6 legs). How many people and flies are in the waiting room?
- Grandmother's clocks
Grandmother's clock is late every hour by half a minute. Grandmother it by set exactly at 8.00 am. How many hours will show after 24 hours.?
Kitchen roller has a diameter 85 mm and width of 337 mm. How many square millimeters roll on one turn?
- Center of gravity
In the isosceles triangle ABC is the ratio of the lengths of AB and the height to AB 10:12. The arm has a length of 26 cm. If the center of gravity T of triangle ABC find area of triangle ABT.
Wjat height reach water level in the tray shaped a cuboid, if it is 420 liters of water and bottom dimensions are 120 cm and 70 cm.
- Water well
Drilled well has a depth 20 meters and 0.1 meters radius. How many liters of water can fit into the well?
- Stamps and albums
Michail has in three albums stored 170 stamps. In the first album, there are 14 more than in the second and in the second is by 1/5 less than in the third. How many stamps are in the first album?
- Parallelogram ABCD
The area of parallelogram ABCD is 41 cm2. Points M and N are the midpoints of the sides AB and BC. What is the area of a quadrilateral MBND?
- Washing machine
The price of washing machine was decreased by 24% and then by 59 € due small sales. After two price decreases cost € 300. How much was originally cost?
- Parallelogram +ľ
| AB | = 76cm, | BC | = 44cm, angle BAD = 30 °. Find the area of the parallelogram.
- Gold coin
Gold coin contains 963 promile pure gold, which is 8.39 g. What is the weight of coin in grams?
Less than 20 children is played various games on the yard. They can create a pairs, triso and quartets. How many children were in the yard when Annie came to them?
- Chord 4
I need to calculate the circumference of a circle, I know the chord length c=19 cm and the distance from the center d=33 cm chord to the circle.
- Alcohol 2
Two types of alcohol one 70% and second 61% give 11 liters of 57% alcohol. How many liters of each type are in the mixture?
The area of trapezium is 35cm2 find its altitude if the bases are 6cm and 8cm.
- Tetrahedral prism - rhomboid base
Calculate the area and volume tetrahedral prism that has base rhomboid shape and its dimensions are: a = 12 cm, b = 70 mm, v_a = 6 cm, v_h = 1 dm.
- Every day 7 pages
Adelka reads the book every day 7 pages. When she reads one more page a day she will read it three days earlier. How long will Adelka read a book? How much does a book of pages have?
- The ship
The ship went upstream speed of 20 km/h in relation to water. River flows at speed 10 km/h. After half an hour, he stopped and returned downstream to the starting point. How long it took way back when even if downstream speed of ship is 20 km/h in relation
We burned two unequally thick and long candles. Longer burnt for three and a half hours and shorter for five hours. After two hours of burning it was identical. How many times was longer candle longer then shorter?
Calculate the surface area and volume of a prism with a body height h = 10 cm and its base has shape of a rhomboid with sides a = 5.8 cm, b = 3 cm and the distance of its two longer sides is w = 2.4 cm.