Math practice for 13 year olds - page 397 of 419
Number of problems found: 8380
- Mushrooms
Fresh mushrooms contain 94% water and dried 9%. How many kilograms of fresh mushrooms are needed to collect to get 10 kg dried? - Against each other
From two points, A and B distant 29 km at the same time started two cars against each other at speeds 82 km/h and 72 km/h. How long do cars meet, and what distance passes each of them? - Motor physics
A car is traveling at 104 km/h on the highway. The pulling power of the motor is 10 kN. Find the engine power in kW. - Ratio
Unfold number 3690 in the ratio 15:11:4. - Parquet floor
Three workers laid the parquet floor for 2.301 hour. The first would do this work alone 7 hours, the second in 6 hours. For how many hours would this work for the third worker if he worked alone? - Inflow - outflow
The tank will fill by inflow for 56 minutes and empties by outflow for 77 minutes. How long does it take to fill the tank if it is open to inflow and outflow? - Painters
The first painter painted the fence himself for 10 hours, the second painter 2.7 hours sooner than the first, and the third painter slowest up to 21 hours. How long took them to paint the fence if they worked together? - OPT
What is the perimeter of a right triangle with the legs 11 cm and 24 cm long? - Elevation
What must be an observer's elevation so that he may see an object on the Earth 866 km away? Assume the Earth to be a smooth sphere with a radius 6378.1 km. - Air
The room is 35.6 m long, 19.6 dm wide, and 591 cm high. How many people can simultaneously be in this room if, for hygiene reasons, is calculated 5000 dm³ of air per person? - Roller
Roller has a diameter of 0.89 m and a width of 225 cm. How many m² of road level when he turns 30-times? - Metallurgical enterprise
Metallurgical company daily produces 501 tons of cast iron. How many tons of coke does it burn to melt cast iron when 14 tons of cast consumes 10 tons of coke? - Accidents
The count of accidents in 1991 caused 8444 women, which is 9%. How many men caused the accidents? - Map - climb
On the map of the High Tatras, on a scale of 1:11000, are cable car stations in the Tatranska Lomnica and the Skalnate Pleso with a distance of 354.6 mm. The altitude of these stations is 949 m and 1760 m. What is the average angle of climb on this cable - Bottle
Bottle with wine costs 42 USD. Wine is 11 USD more expensive than the empty bottle. How much is the bottle itself? - Circumferential angle
Vertices of the triangle ΔABC lay on the circle and are divided into arcs in the ratio 10:8:7. Determine the size of the angles of the triangle ΔABC. - Center of the cube
The Center of the cube has a distance 40 cm from each vertex. Calculate the volume V and surface area S of the cube. - Lie/do not lie
The rule f(x) = -x-10 gives the function. Find whether point C[5; -15] lies on this function. Solve graphically or numerically and give reasons for your answer. - Simple interest
Peter put into bank 853 euros deposit. After 7 years on account, overall was 984 euro. What was the interest rate if the bank added simple interest? - Balls
Three metal balls with volumes V1=12 cm3, V2=112 cm3, and V3=59 cm³ were melted into one ball. Determine its surface area.
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