Maths practice for 14 year olds - page 71 of 375

Number of problems found: 7497

Nikelin and brass
Calculate the length of brass wire (ró=0.08 microohm m) and nickel (ró=0.4 microohm m) with a diameter of 0.5 mm, which has a resistance of 1 ohm
Cooker wire resistivity
The heating coil of the cooker has a resistance of 70.5 ohms and is made of a wire with a diameter of 0.30 mm and a length of 9.8 m. Determine the resistivity of the material from which it is made.
The grocery
Susan has decided to make grocery combos for her shop. The wholesaler she buys from sells sugar in packets of 20 in a carton, flour in packets of 12 a carton, and 15 bags of rice in a carton. How many of each item should she buy so there are an equal numb
Wire charge current
A constant current of 80mA passes through the wire. What charge passes through the conductor in 1 h?
The sum 28
The sum of the age of a girl and her mother is 38. Next year the mother will be four times as old as her daughter. How old was the mother when her daughter was born?
LED resistor current
Calculate the current I that would race through resistor R5 (720 ohms), resistor R2 (220 ohms), and an LED (U=2V) at a DC 6V source. The resistors are connected in series.
Ava bought
Ava bought snacks for her team's practice. She bought a bag of oranges for $2.71 and a 4-pack of juice bottles. The total cost before tax was $6.75. Write and solve an equation that can be used to determine juice cost, how much each bottle of juice cost
Money ratio division
Kuba, Martin, and Pepa earned CZK 1,813. They divided them in the ratio Cuba: Martin 6:5. Martin: Pepa 2:3. How many crowns did each of them get?
Tourist group distance
A group of tourists split up at the intersection of two perpendicular paths. One group walked at a speed of 5.3 km/h. Second group 4.1km/h. How far were the two groups from each other after 1h 25min?
Triangle perimeter ratio
The ratios of the sides of a right triangle are 3: 4: 5. How long is the hypotenuse if the entire perimeter of the triangle is 48 cm?
Orchard tree rows
There are 390 trees arranged in rows in the orchard. How many rows are there if each row has the same number of trees greater than 30 and less than 40?
Segment center coordinates
A (a1, 4) B(7, -2) segment AB has a center where both coordinates are equal
The ages 2
The ages of the two persons differ by 18 years. Twelve years ago, the elder one was 4 times as old as, the younger one. The present age of the elder one is:
Sheep white black
Forty sheep graze in the meadow. There are 4 times more whites than blacks. How many white and how many black sheep are grazing in the meadow?
Begonia seed sowing
The 94 m² flower bed is to be planted with begonias. An area of 2 dm² is needed for one seedling. How many grams of seeds should be sown if 1 g of seeds contains approximately 5000 seeds? Losses when growing seedlings are usually 30%.
Almond fat daily
The daily need for fat for a person is 80g on average. Almonds contain 45% fat. How many grams of almonds would a person have to eat if he wanted to cover his daily need for fats by eating only almonds?
Cube volume decrease
By what percent does a cube's volume decrease if its edge length is reduced by a quarter?
Milk butter fat
Cow's milk contains an average of 3.6% fat. How many liters of milk are needed to make 250g of butter? Butter contains 82% fat.
Square perimeter increase
By what percent does the area of a square increase if its perimeter increases by one-fifth?
Nitric lime nitrogen
Nitric lime contains an average of 19% nitrogen and 55% calcium oxide. How many grams of nitrogen per 1 m² if we bought a 25 kg package and thereby evenly fertilized a garden of 12 a?

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