Examples for 8th grade - page 55
- Tangents construct
Circle is given k (S; 2.5 cm) and an outer line p. Construct a tangent t of the circle that has with a line p angle 60°. How many solutions has the task?
Welder do the job for six hours, the second one for 8 hours. How long do the job third welder if all together can do job in 2 hours?
- Calcium and citality
The daily dose of calcium obtained using 0.75 liters of milk and 60 grams of cheese. A/ At the morning I drank half a liter of milk. How much cheese I must eatto eat a daily dose of calcium? b / I ate 50 grams of cheese, how much milk I must drink? c /.
Master shoemaker has three apprentices. First do one pair of boots for two days, second for 1 day, third on 1.5 day. If they worked together, for how long it would take made a couple of boots?
- Oil tank and pipes
The underground oil tank can be filled by two oil pipelines. The first is filled in 72 hours and the second in 48 hours. How many hours from the moment when first pipeline began to fill the oil is it necessary to start filling it with the second to fill in
Three copiers will do the same in an hour k copies. How many copies would be done in an hour by four such copiers? ?
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
- Slope form
Find the equation of a line given the point X(10, -2) and slope -1.2. Arrange your answer in the form y = ax + b, where a, b are the constants.
- Rotating cone
Calculate the volume and the surface area of a rotating cone of base radius r = 2.3 dm and a height h = 46 mm.
- Chord 3
What is the radius of the circle where the chord is 2/3 of the radius from the center and has a length of 10 cm?
- Chocholate pyramid
How many chocolates are in the third shelf when at the 8th shelf are 41 chocolates in any other shelf is 7 chocolates more the previous shelf.
1 t of sea water contains 25 kg of salt. How many tons of seawater must be evaporated to obtain 2 q of salt?
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?
- Supplementary angles
One of the supplementary angles are three times larger than the other. What size is larger of supplementary angles?
Calculate the area of right triangle ΔABC, if one leg is long 12 and its opposite angle is 31°.
Peter and Franta threw to the basket. Each had 20 attempts. Peter scored thirteen and twelve Franta. Give them success in percentage.
- The field
The player crossed the field diagonally and walked the length of 250 m. Calculate the length of the field, circumference if one side of field 25 meters.
- Rhombus A2p
Rhombus area is 13 cm2 and its height is 5cm long . Determine a perimeter of this rhombus.
James paints a fence. If every day instead of 14 planks painted 16 would be done on one day earlier. How many of planks has a fence altogether?
- Internal and external angles
Calculate the remaining internal and external angles of a triangle, if you know the internal angle γ (gamma) = 34 degrees and one external angle is 78 degrees and 40 '. Determine what kind of triangle it is from the size of its angles.