Maths practice for 14 year olds - page 84 of 371
Number of problems found: 7415
- Water - heat
Calculate the mass of water that gave off 520.5 kJ of heat when cooled from 69°C to 27°C.
- The temperature 30
The temperature in Hubby's office is 16 degrees Celsius, and the temperature outside his office is negative 7 degrees Celsius. What is the difference in temperature in these two places?
- At 5:00
At 5:00 AM, the room temperature was 20°C. After six hours, the reading was 28°C. The temperature rose to how many degrees? What was the average change in temperature per hour?
- Measurements 71584
On the plan, the rectangular factory hall has dimensions of 30 cm and 16 cm at a scale of 1:500. Calculate the actual measurements.
- Two alloys
Two alloys, Y and Z, are each made up of zinc, tin, and copper. In alloy Y, the ratio of zinc to tin is 2:5, and the ratio of copper to tin is 4:3. Find the ratio of copper:zinc:tin in alloy Y.
- Shadows
At the park, a young woman who is 1.72 meters tall casts a 3.5 meters shadow at a certain hour. What is the height of a tree in the park that, at the same time, casts a 12.3 meters shadow?
- Tower roof
The tower's roof is a regular 4-sided pyramid with a height of 4m and an edge of the base of 6m. 25% of the roof covering was found to be damaged. How many square meters of coverage are needed to repair the roof?
- Originally 71464
The father originally wanted to divide the financial amount between his sons in the ratio of 7:6. However, he then split it at 6:5 (in the same order). One of the sons got angry that he should have received 120 euros more. How many euros did each son rece
- Cube-shaped 71414
Mother and daughter Susan are wrapping presents for father. Maťko has a cube-shaped box with dimensions of 9 cm, 3 cm, and 7 cm, and Zuzka has a box in the shape of a cube with an edge length of 3 cm. How many square cm of wrapping paper will they use in
- Base diameter
Calculate the volume and surface of a cone whose base diameter is 6 cm and height is 0.9 dm.
- Circumference 71304
The PQR triangle with a circumference of 25.5 cm has sides in a ratio of 4:6:5. Determine the lengths of its sides.
- Quarter of unknown number
If we subtract a quarter of a number from the number 12, we get the number -5. What's that number?
- Digits - numbering
We used 1533 digits to number the rough book. How many pages does this book have if each page, including page 1, is numbered?
- Cross-section 71254
The steel conductors of the long-distance power line have a cross-section of 5 cm². Calculate the resistance of a steel wire with a length of 2 km if the resistivity of the steel is 13 * 10-8 Ω · m.
- Identical 71234
How many ways can you divide two identical apples and: a) 3, b) 4, c) 5 identical pears between Janka and Mařenka?
- Expression 71224
The operation ♤ is defined by the relation A ♤ B = AB - A - B. What is the value of the expression 5 ♤ (4 ♤ 3) equal to?
- Distinguish 71184
We randomly choose a family with three children. We distinguish between gender and age. Determine the probability that: a) the youngest girl will be among the children b) all children will be of the same sex
- Probability - on the roll
Find the probability that one will fall at least once in three rolls.
- Probability 71164
We roll the dice twice. What is the probability that if an even number falls for the first time, the even number will fall a second time?
- Isosceles 71154
Calculate all interior angles in the isosceles triangle ABC if we know that BC is the base, and we also know: | ∢BAC | = α; | CABCA | = 4α
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