Math practice for 13 year olds - page 54 of 424
Number of problems found: 8477
- 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). - Box
A paper box is in the shape of a cube. 2,400 cm² of paper was used to make it (not including folds for gluing the walls). Calculate the volume of the box. - Frames
A framer is to prepare 23 picture frames with dimensions of 30 cm × 42 cm. The strips from which he makes the frames are 3 metres long. a) How many frames can he make from one strip? b) How many strips will he need? - Find b from LCM
The least common multiple of 2,190 and b is 13,140. What is b? - 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. - 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? - It consumes
A textile machine uses 7/8 metres of fabric to sew a pair of shorts and 3/5 metres more fabric to sew a T-shirt. Determine whether 30 metres of fabric will be enough to sew 12 complete sets, where one set consists of one T-shirt and one pair of shorts. - 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? - Minutes in Percentage
How many minutes is 45% of four hours? - Client
A bank client had €1,320 deposited in her account throughout the year. At the end of the year, €33 in interest was credited to the account. What annual interest rate was applied? - Cheaper skis
In Tesco, skis originally priced at 9,000 CZK were reduced by 30%. In Makro, the same skis were first reduced by 20% and then, a week later, by a further 10%. Where were the skis cheaper in the end? - Maths exam
One third of all students in a secondary school passed the maths exam. Five of these students then failed the maths exam retake. One quarter of all students in the final year of the secondary school passed the maths exam. Calculate the total number of stu
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