Maths practice for 14 year olds - page 171 of 361
Number of problems found: 7214
- Water temperature cooling
The water in the container has a temperature of t1 = 80◦C, the temperature around the container is t2 = 15◦C. The dependence of temperature t on time τ (in minutes) can be expressed approximately by the formula: t = t2 +(t1 −t2)·e^(−0.05·τ) Calculate the - Wheel circumference
The circumference of the first wheel is 0.5 m larger than the circumference of the second wheel. The first wheel turns on the 36 m track as many times as the second on the 30 m track. Determine the rims of both wheels. - The conical
The conical candle has a base diameter of 20 cm and a side of 30 cm. How much dm³ of wax was needed to make it? - Birthdays
In a classroom, students give candy to their classmates on their birthdays. The birthday student gives one candy to each classmate but does not receive one themselves. A total of 650 candies were given out over the course of the year. How many students ar - Car motorcyclist meeting
The distance from Olomouc to Brno is 77 km. At 4:00 PM, a passenger car left Olomouc for Brno at an average speed of 100 km/h. Half an hour later, a motorcyclist drove from Brno to Olomouc at an average speed of 80 km/h. What time do they meet? - Two trains
The train runs at speed v1 = 72 km/h. The passenger sitting on the train observed that a train long l = 75 m in 3 s passed on the other track in the opposite direction. Calculate the speed of this train. - Defective bulb probability
There are 30 broken-down packages with 2,000 light bulbs. What is the probability that a randomly selected light bulb is defective? - Quadrilateral shelter
The shelter has the shape of a regular quadrilateral pyramid without a front wall. The length of the base edge is 3 meters, and the shelter's height is 3.5 meters. How much canvas must be bought to sew it if we have to increase consumption by 20% for fold - Aluminum volume expansion
The aluminum container has an internal volume of 0.75 l at 20 °C. How does this volume change if the temperature increases by 55 °C? A = 24.10-6 1/K. - Pulley pulling force
We lift a box weighing 50 kg onto a railway wagon with precise movement along a 3 m track. We will use a fixed pulley. What is the pulling force on the free end of the rope? - Cooker
A current of 2 A passes through the immersion cooker at a voltage of 230 V. What work do the electric field forces do in 2 minutes? - Production increase percentage
The company produced 300 vehicles a day. What percentage did production increase when they made 1,560 vehicles in 5 days? - Herbs drying
By drying, 75% of the weight of the herbs is lost. How many fresh herbs do you have to dry if you want to hand in 1.2 kg of dried herbs? - Vehicle meeting
A truck left place A at 8:00 a.m. at a speed of 60 km/h. From place B, which is 225 km from A, a car drove towards it at a speed of 90 km. Determine when and how far from place A the vehicles meet. - Rectangular land
On a rectangular plot of land with dimensions of 35 m and 18.5 m is a house with a square floor plan with a side of 14 m. What % of the land is not occupied? - Car meeting calculation The distance between K and L is 150 km. At 8.00, a car left place K at a speed of 60 km/h. At 9:00 a.m., a second car drove towards him from location L at 75 km/h. At what time will they meet, and how far from L will it be?
- Steel wire expansion
The steel wire (α = 11.5. 10-6 1/K) has a length of 100 m at -15 °C. Find its length at 45 °C. - Diameter = height
The cylinder's surface, the height of which is equal to the diameter of the base, is 4239 cm square. Calculate the cylinder volume. - Cone roof
How many m² of roofing is needed to cover a cone-shaped roof with a diameter of 10 m and a height of 4 m? Add an extra 4% to the overlays. - Double probability
The probability of success of the planned action is 60%. What is the probability that we will achieve success at least once if this action is repeated twice?
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