Maths practice for 12-year-olds - page 47 of 354

Number of problems found: 7066

Teeth
An adult has a total of 32 permanent teeth. How many of them are molars if 1/4 of the teeth are incisors, another quarter are molars, and the remaining quarter are canines?
Fuel and oil ratio 2T
4 litres of gasoline are to be mixed with oil in a ratio of 33:1. How much oil is needed?
Products - defective
Among 125 products, 56 were defective. What percentage of the products are without defects?
Evaluate expression
Evaluate the following expression: −1 2/7 + (−2 1/4) + 1/2 =
Average 110
The average of five numbers is 1.3. What is their sum? What is the arithmetic mean of the numbers 0.04, 0.014, and 0.21? The arithmetic mean of four decimal numbers is 2.5. Three of these numbers are 1.8, 0.65, and 3.1. What is the fourth number?
Two cuboids
A cuboid has dimensions of 2 m × 3 m × 4 m. We increase the length of all edges by 50 cm. 1. By what percentage does the surface area of the cuboid increase compared to the original? Round the result to the nearest whole percent. 2. By what percentage doe
Buses 7
Two bus lines leave the bus stop according to the following schedule: A) at 8:00, every 6 minutes until 23:00 B) at 8:00, every 14 minutes until 23:00 How many times will buses of both lines leave the bus stop simultaneously between 8:01 and 20:00?
Heating water
5 kg of water warmed up by 10 °C. How much heat did the water absorb? (Remember that 1 kg of water requires 4,200 J of heat to raise its temperature by 1 °C.)
Dividing Fruit by Ratio
60 kg of fruit were divided between the KOP store and the FRESH store in a ratio of 2:3. How many kilograms did the FRESH store receive?
Reading a Book Faster
Jana received a new book. She wants to read it in 8 days. If she read 6 more pages a day, she would finish the book two days earlier. How many pages does the book have?
Multiplying Absolute Value and Reciprocal
What is obtained by multiplying the absolute value of −0.7 by the reciprocal of 10?
Raspberry juice
How much will the scout leader pay for drinks for the children, if a third of the children had raspberry juice for 10 CZK, half of the children had sparkling water for 15 CZK, and the remaining 4 children had kola for 20 CZK?
Dependent variables
A printer prints k sheets in n seconds (k, n ∈ ℕ). Express the number of sheets that the printer prints in 5 minutes in terms of k and n.
Concert organizers
800 people came to the concert, which was a quarter more than the organisers had expected. How many people did the organisers expect?
Coal Used and Remaining
We used one quarter of the coal we bought, leaving us with 12 q. How much coal did we buy?
Cutting a cuboid
A cuboid can be cut into 200 cubes, each with a volume of 8 dm³. Calculate how many cubes with a volume of 1 cm³ this cuboid can be cut into without a remainder.
Finding the Second Number
The arithmetic mean of two numbers is 10. One of the numbers is 2. What is the other number?
TEV physical education
Students lined up in rows of three in a physical education class, and then in rows of four, and each time there was exactly one student left over. What is the minimum number of students that could be in the gym?
Boxes of wafers
Wafers measuring 11¾ cm × 4⅖ cm × 1⅔ cm are packed in rectangular boxes measuring 23½ cm × 26⅖ cm × 6⅔ cm. What fraction of the volume of the box does one wafer occupy?
MO Z7 2025
Adela and Susan ate plums. On the first day, Adela ate three quarters of what Susan ate that day. On the second day, Susan ate three halves of what Adela ate that day. Together, they ate 31 plums over the two days, and each girl ate a whole number of plum

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