Examples for 8th grade - page 10
- Strange x
For what x is true ??
- Metallurgical enterprise
Metallurgical company daily produces 873 tons of cast iron. How many tons of coke it burns to melt cast iron when 17 tons of cast consumes 13 tons of coke?
- Trapezoid MO-5-Z8
ABCD is a trapezoid that lime segment CE divided into a triangle and parallelogram as shown. Point F is the midpoint of CE, DF line passes through the center of the segment BE and the area of the triangle CDE is 3 cm2. Determine the area of the trapezoid A
The store got three kinds of tissues - 132 children, 156 women and 204 men. Tissues each species were packed into boxes after the number of pieces the same for all three types (and greatest). Determine the number, if you know that every box has more than 6
- Two doctors
Doctor A will determine the correct diagnosis with a probability 80% and doctor B with a probability 72%. Calculate probability of correct diagnosis if patient is diagnosed by both doctors.
Coffee from the machine in the cup cost 25 cents. Coffee is 20 cents more expensive than the cup. How much is the cup?
Marie earns 1.8 liters of blueberries for 1.2 hours, Peter 2.6 liters for 1.2 hours. How long have earns together one liter?
- The bridge
Across the circle lakepasses through its center bridge over the lake. At three different locations on the lake shore are three fishermen A, B, C. Which of fishermen see the bridge under the largest angle?
The cube weighs 18 kg. How weight is cube of the same material, if its dimensions are 3-times smaller?
- Eiffel Tower
Eiffel Tower in Paris is 300 meters high, is made of steel. Its weight is 8000 tons. How tall is the tower model made of the same material, if it weigh is 4.8 kg?
- Mountain railway
Height difference between points A, B of railway line is 38.5 meters, their horizontal distance is 3.5 km. Determine average climb in permille up the track.
The longer leg of a 30°-60°-90° triangle measures 7. What is the length of the shorter leg?
Area of square garden is 6/7 of triangle garden with sides 96 m, 60 m and 60 m. How many meters of fencing need to fence a square garden?
- Square and circles
Square with sides 82 km is circumscribed and inscribed with circles. Determine the radiuses of both circles.
On coins found was stated that from the year 87 BC. It is right?
- The dice
What is the probability of events that if we throw a dice is rolled less than 6?
Calculate the perimeter and area of rhombus whose diagonals are 15 cm and 27 cm long.
Siblings collect a 2-crowns and 5-crowns. Together have 80 coins with a total of value 310 crowns. How many saved two-crowns and how many five-crowns?
- Bus vs. train
Bus started from point A 15 minutes before the train started from the same place. The bus went an average speed of 49 km/h, train 66 km/h. To point B train and bus arrived simultaneously. Calculate time of train journey, if train and bus travelled the.
In how many ways can be placed 6 athletes on the podium at the Olympics? Depend on the color of the metal.