Examples for 8th grade - page 33
Dano had 20 raspberries. John had 90% more raspberries than Dano. Determine how many raspberries have Dano and Juraj together.
- Cylinder twice
If the radius of the cylinder increases twice, and the height is reduced twice, then the volume of the cylinder increases (how many times?):
- Four classses
Students of all 7, 8 and 9 classes in one school may take up 4,5,6 and 7 abreast and nobody will left. How many is the average count of pupils in one class if there are always four classes each grade?
- 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?
Ten workers must pave road street for 22 working days. After four days were for speeding up work added two more workers. a) After how many work days now workers completes the paved road? b) How many working days it took a total paved road?
Gearing consists of two wheels, one is 88 and second 56 teeth. How many times turns smaller wheel to fit the same teeth as in the beginning? How many times will turn biggest wheel?
- Painter 3
Dad want to paint wall high 250 cm wide and 230 cm with wallpaper. How many meters must buy wallpaper if wallpaper width is 60 cm?
- Roof tiles
The roof has a trapezoidal shape with bases of 15 m and 10 m, height of roof is 4 meters. How many tiles will need if on 1 m2 should be used 8 tiles?
- Three friends
Divide 570 euros to three friends so that first will get 50 euros less than the second and third twice more than the first. How many euros will get everyone?
- The book
If one day you read p pages, you will read the book 24 days. If you read each day 10 pages more, you would read a book in 16 days. How many pages have the book?
Enterprise sold 7/12 of their products to foreign markets and 2/5 of the remainder sold at home. How many % of the products is still in stock?
Between adjacent levels are 15 stairs. If step will be 1.2 cm lower there would be 16 stairs. What is the stair height?
The first alloy is a mixture of two metals in the ratio 1:2, the second is a mixture of same metals in the ratio 2:3. At what ratio we have these two alloys put into the furnace to obtain a new metal alloy with ratio 17:27? (All three ratios correspond to.
- Complementary angles
Two angles are complementary. If one angle measures 49°, what is the measure of the second angle?
- Isosceles III
The base of the isosceles triangle is 24 cm area 416 cm2. Calculate the perimeter of this triangle.
Mr. Gherkin use for fertilization 9% solution of fertilizer. 7 liters of it still left. How much water must be added to the solution to make only 5% solution?
A passenger train traveled for 4 hours 136 km. 2.7 hours after its departure started fast train and caught it on 324 km. How many km/h is different its average speeds?
- Squaring the Circle
Calculating side of the square with the same area as the circle of radius 18.
The clock shows 12 hours. After how many minutes will agle between hour and minute hand 80°? Consider the continuous movement of both hands hours.
- Right triangle
Right triangle ABC with side a = 16 and the area S = 80. Calculate the length of the remaining sides.