Examples for 8th grade - page 33
Points A[1,5] and B[-4,-5] are adjacent vertices of the square ABCD. Calculate area of the square ABCD.
- Event probability
The probability of event G in 9 independent experiments is 0.48. What is the probability that the event G occurs in one experiment (probability is same)?
Agricultural cooperative has increased the number of housed cows by 14% to 285 units. By how many cows increased agricultural cooperative the number of cows?
For nearly full tank of 40 liters of gasoline chauffeur paid 54 euros. How many euros it will cost to go 250 km long if the car has an average fuel consumption 7 liters per 100 kilometers?
Perimeter of rectangle is 48 cm. Calculate its dimensions if they are in the ratio 5:3 (width:height)
What amount of 80% solution and what amount of water is needed to mix in order to obtain two liters of 60% solution of this mixture?
- Age ratios
The ratio of the age of the mother and daughter is 5:2 and after seven years the ratio will be 2:1.Before how many years was born the daughter?
- Unknown number
Identify unknown number which 1/5 is 40 greater than one tenth of that number.
- Two trains
Two trains go at each other. First at speed 40 km/h and the second at speed 60 km/h. At what distance will be 30 minutes before they will meet?
- Bronze, tin and copper
Bronze is an alloy of tin and copper. An alloy of 10% tin and 90% copper is Gunmetal. If it contains 20% tin and 80% copper, it is bell metal. How many tons of molten bell metal and how many tons of copper is needed to make 100 tons of Gunmetal?
From 55% and 80% spirit we would like to produce 0.2 kg of 60% spirit. How many of them we must use in a solution?
- Colour - billboard
Shelftalker has the shape of a parallelogram. Its length is 4.9 m and the corresponding height is 3.5 meters. Calculate how much (kg) paint must purchase to redecoration if 1 kg cover 4 m2 of shelftalker surface.
- Borrowed book
Jane must as soon as possible return a borrowed book. She figured that when she read 15 pages a day return book in time. Then she read 18 pages a day and then return the book one day before. How many pages should have a book?
Parents piggybacking children on vacation to its grandmother and grandfather at a city distant 150 kilometers. They agreed to meet halfway. Parents will be travel at 90 km/h, grandmother and grandfather at 60 km/h. Parents depart at 12:00 hours. When grand
- Water level
The glass container has a cuboid shape with dimensions of the bottom 24 cm and 12 cm. The height of water is 36 cm. Calculate the volume of the body, which are sunk into the water if the water level rise by 3 cm.
Theatrical performance was attended by 480 spectators. Women were in the audience 40 more than men and children 60 less than half of adult spectators. How many men, women and children attended a theater performance?
- Scale 3
Miriam room is 3.2 meters wide. It is draw by line segment length 6.4 cm on floor plan. In what scale it is plan of the room?
Weight of cargo car is 761 kg. Weight of car is 23% of the total weight of car+cargo. What is the weight of the cargo load?
120 vehicles parking on the morning. Pasenger car is charged 20 CZK, 50 CZK per bus. The guard collected for parking 2640 CZK in total. How many cars and how many buses stood in the parking?
- Mushrooms from the forest
Magda and Tereza goes to pick mushrooms. Total found 70 mushrooms. Magda found that between fungi found 5/9 bedel. Tereza discovered that she found among fungi are 2/17 champignons. How many mushrooms found Magda?