Math practice for 13 year olds - page 65 of 414
Number of problems found: 8279
- Boiler room
If only the first boiler is running, the coal supply lasts 8 days. If only the second boiler is running, the supply lasts 12 days. If only the third boiler is running, the supply lasts 6 days. How many days in total will the coal supply last if only the f - Refrigerator - discount
The refrigerator was first discounted by 20% and then increased in price by 5%. Now the Zmrzlin family bought it for 420 euros. How much was the refrigerator before the discount? - Individual
To prepare 14 kg of cheese with 45% dry matter, three types of cheese mixtures were blended. The first mixture weighed 5 kg; the second weighed 3 kg and contained 14 percentage points more dry matter than the first. The third mixture, which had twice the - Camp room distribution
Fifty pupils were in the camp; they lived in double and triple rooms. They occupied 20 rooms, many of which were two- and three-story. Please proceed. - Source internal resistance
A load of 23.5 ohm is connected to an ideal voltage source of 30 V, and a current of 1.2 A passes through the circuit. Determine the magnitude of the source's internal resistance and the short-circuit current. - Consecutive even sum
The sum of five consecutive even numbers is -10. What are the numbers? - Part-timer
Seven part-timers paint 280 m of railings in 5 hours. How many meters of railing will nine part-timers paint in 4 hours? - Cyclist opposite distance
A cyclist left Olomouc in the direction of Zábřeh in 6 h 30 min at an average speed of 24 km/h. At 7:40 a.m., a cyclist left Olomouc opposite Ostrava at an average 36 km/h rate. At what time will they be 112 km apart? - Clock face
On the circular face of the clock, we connect the points corresponding to the numbers 2, 5, and 9 to each other, which creates a triangle. Calculate the sizes of all interior angles. - Trapezoid plot fence
The plot of land for constructing family houses is shaped like a rectangular trapezoid with bases of 21 m and 11.2 m. For CZK 2,500 per square meter, the value of the land is calculated at CZK 1,352,400. What would be the length of wire mesh needed to fen - Cone surface volume
A cone of rotation with a radius of 32 cm and side length s = 65 cm is given. Calculate the surface area and volume. - Tennis serve percentage
The tennis player won precisely 55% of the balls during his serve. In doing so, he served less than thirty times. How many times did he serve? - Parallelogram diagonal size
Given is the parallelogram KLMN, in which we know the side sizes/KL/ = a = 84.5 cm, /KN/ = 47.8 cm, and the angle size at the vertex K 56°40'. Calculate the size of the diagonals. - Mast angles and height
Calculate the height of the mast, whose foot can be seen at a depth angle of 11° and the top at a height angle of 28°. The mast is observed from a position 10 m above the level of the base of the mast. - The rotation cone
The rotation cone with a height of 18 cm and side length s = 45 cm is given. Calculate the surface area and volume. - Pool man woman
A total of 680 adults visited the swimming pool yesterday, among whom there were 30% fewer men than women. How many men visited the swimming pool yesterday? - Soda bottles factory
Two different filling machines fill soda bottles to order. If the first machine worked alone, it would need a third less time to complete the order. How long would it take each machine to complete the job independently if the faster machine worked for 96 - Pupil room distribution
Pupils on ski training lived in 29 rooms, some of which were 4-bed, others 5-bed. How many were there when there were 120 children? - Remaining
Mum baked buns for dinner. Dad ate 1/3 of them. Then George came and ate a quarter of the remaining buns. After George, Martin came and ate a third of what was left. Annie ate half of the remaining buns, and Mum was left with four buns. How many buns did - In the primary
In a primary school every year a knowledge competition is organised, in which each competitor can get at most 15 points. This year the average point achievement of the competitors, rounded to tenths, was 10.4. Jožko realised after the competition that som
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