Maths practice for 14 year olds - page 42 of 367
Number of problems found: 7336
- Clothing
Winter clothing was first reduced by 20% in the spring, and then the new price was reduced by a further 25%. What was the original price of a winter jacket if it was sold after the double discount for 1,050 CZK? - Aluminum ignote
At what temperature did the temperature stabilise if an aluminium ingot weighing 45 kg, initially at 15 °C, received 4.8 MJ of heat? The specific heat capacity of aluminium is 896 J/(kg·°C). - Didactic test B0
A tourist cycled 28 km on an asphalt road and 25 km on a dirt road, taking 3 hours and 36 minutes in total. At what speeds did the tourist travel each section if he rode 1.4 times faster on the asphalt road than on the dirt road? - Capacity of iron
What was the initial temperature of an iron object weighing 30 kg that absorbed 3.5 kJ of heat when heated to 39 °C? The specific heat capacity of iron is 450 J/(kg·°C). - Calorimetric equation
A 200 g aluminium cylinder at 180 °C was dropped into 3 kg of water at 25 °C. At what temperature did the mixture stabilise? The specific heat capacity of water is 4,200 J/(kg·°C) and of aluminium is 896 J/(kg·°C). - By mass
How much heat must be supplied to completely melt 45 kg of potassium initially at 22.4 °C and bring it to a temperature of 98 °C? The specific heat of fusion is 25.5 kJ/kg, the melting point is 63.32 °C, and the specific heat capacity of potassium is 757. - Crowbar - lever
How much force must be applied to the end of a 2.4 m long crowbar to lift a door weighing 220 kg, if the crowbar rests on the ground and the door stands on it 35 cm from the ground-end? - In the parking lot 2
There were 12 cars in a car park: 5 green, 4 blue, and 3 red. What is the probability that the last car left in the car park is blue or green? - Two-kilogram bread
Farmers harvested 3,000 kg of rye from one hectare, from which they obtained 2,500 kg of flour. From 3 kg of flour, 4 kg of bread can be made. Calculate how many m² of land were needed to grow the rye required for one 2-kilogram loaf of bread. - Borrowed
Mr. Douda borrowed 200,000 Sk from the bank at an annual interest rate of 15.4%. He will repay the loan after four years. How many korunas will he have to repay in total? - Emptying a tank
A water tank can be emptied by the first pump in 12 hours, by the second in 9 hours, and by the third in 4 hours. How many hours will it take to empty the tank if all 3 pumps are turned on simultaneously? - Gross Salary Calculation
An employee receives a net salary of 5,000 after a 15% income tax withholding. What was the gross salary? - Prepare
From two types of tea priced at 1,500 Sk/kg and 2,100 Sk/kg, 29 kg of a mixture priced at 1,650 Sk/kg is to be prepared. How many kilograms of each type of tea should be mixed? - Chord 24
A chord of length t = r√2 divides a circle with radius r into two circular segments. What is the ratio of the areas of these two segments? - Insulating a house
Five workers are insulating a house at a pace that would allow them to finish the job in 18 days. After three days of work, two workers were called away to another construction site. In how many more days will the remaining workers finish the job? - Advertising column
An advertising column has the shape of a triangular prism. The height of the prism is 3.5 metres, and the lengths of the base edges are 1.1 m, 2 m, and 2 m. The lateral surface of the prism forms the advertising space. The town pays 35,000 CZK for its pro - Sandwiches, cola and desserts
At a dance party, sandwiches, cola, and desserts were prepared for refreshment. 18 people ate desserts, 29 people ate sandwiches, and 32 people drank cola. Two people did not consume any kind of refreshment. All kinds were consumed by 5 people. Cola and d - Repeatition not allowed
How many four-digit numbers can be formed from the digits 3, 5, 8, and 9 if no digit may be repeated? - Kilometers of the journey A cyclist travelled 199 km over three days. On the first day, he travelled four times as far as on the second day, and on the second day, he travelled 7 km less than on the third day. How many kilometres did he travel each day?
- Plums - a quarter
How many plums were originally in the bowl if Iva ate a quarter, Jana ate a fifth, Mike ate three eighths, and 7 were left?
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