# - 7th grade (12y) - math problems

#### Number of problems found: 2784

• Iron Iron ore contains 54% iron. How much ore is needed to produce 23 tons of iron?
• Carbon dioxide Calculate how many grams of oxygen are in 50 g of carbon dioxide CO2. Relative atomic mass of oxygen is 16 and of carbon is 12.
• Air mass What is the weight of the air in a classroom with dimensions 10 m × 10 m × 2.7 m ? The air density is 1.293 kg/m3.
• Barrel of oil Barrel of oil weighs 283 kg. When it mold 26% oil, weighed 216 kg. What is the mass of the empty barrel?
• Extreme temperatures USA hit extreme heat wave. Calculate percentage of the air temperature change from normal summer temperature 23 °C to 40 °C.
• Copper plate Copper plate length 3.2 m and width 50 cm weighs 55.42 kg. What is the plate thick, if 1 m3 of copper weighs about 8700 kg?
• Magnification of the square If we increase the square side, increase the content of the 70 %. About what percentage was increased his sides?
• Promile Calculate the 4.6 ‰ of 199.
• Circle and angle What is the length of the arc of a circle with radius r = 207 mm with cental angle 5.33 rad?
• Slovakia banks It is unwritten rule that the larger bank in Slovakia (number of clients, balance sheet) the worst / more expensive services offered to clients. Perhaps it is customs and herd customers that prefer only trio SLSP, VUB and Tatrabanka. Calculate how many ti
• Tesco Clubcard Bernard got on quarterly billing vouchers for Tesco ClubCard taking goods worth 2.3 Eur. Calculate how much per month in Tesco stores bought goods on average. Tesco ClubCard works for every Euro spent you get one ClubCard point that will be converted to 1 I longer watch processors for Socket A on ebay, Athlon XP 1.86GHz with a PR rating of 2500+ costs \$7 and Athlon XP 2.16Ghz with a PR rating of 3000+ currently cost \$16. Calculate: About what percentage of the Athlon XP 2.16Ghz is powerful than Athlon XP 1
• Quiz Tested student answered correctly on a 4/ 8 questions. Wrong answers was 16. How many questions answered?
• Trapezium zoom How many times increase area of trapezoid if all sides and altitude increase 5 times?
• Barrel with liquid Barrel with grain weight 297 kg. When it shed 48% of grain, ha weight 174 kg. What is the weight of empty barrel?
• Sumo competition In the competition for the heaviest man was 5 competitors. The first three together weighed 553 kg. What is the minimal weigt of winner, if a contestant weighed with an accuracy of one kilogram.
• Triangle angles The angles α, β, γ in triangle ABC are in the ratio 6:2:6. Calculate size of angles. Convert magnitude of the angle α = 136°18'10" to radians: Calculate the side of the rectangle, if you know that its area is of 2590 m2 and one side is 74 m. VAT is a tax on which the state artificially betrays goods and services for final consumption. VAT in Slovakia is 20%. Calculate how much percent pay less tax residents of Japonska, when VAT is only 5%.