Math practice for 13 year olds - page 359 of 424
Number of problems found: 8476
- Bob and Bobek
Bobek runs from the hat at an average speed of 12 km/h at 10:20. At what time must Bob run out at a speed of 18 km/h to catch him 9 kilometers from the hat? - Dwarfs
Four dwarfs prepared firewood for Snow White and could finish in 580 minutes. After an hour and a half, they recruited friends and finished the work in 280 minutes. How many dwarfs did they recruit? - Arc-sector
arc length = 17 cm area of sector = 55 cm² arc angle = ? the radius of the sector = ? - Substitute a number
I think the number is when you substitute it in the expression (x-2). (2x - 1), you get zero. What number can it be? - Pedestrian and the cyclist
Pedestrians and cyclists went against each from the two cities that are distant 40 km. The pedestrian started 30 minutes before the cyclist and walked at an average speed of 5 km/h. What speed went the cyclist when met after 120 minutes from the start of - Beer permille
In the 5 kg of the blood of an adult human after three 10° beers consumed in a short time is 6.6 g of alcohol. How much is it per mille? - Chords centers
The circle has a diameter of 17 cm, upper chord |CD| = 10.2 cm, and bottom chord |EF| = 7.5 cm. The chords H and G midpoints are |EH| = 1/2 |EF| and |CG| = 1/2 |CD|. Find the distance between the G and H if CD II EF (parallel). - Shopping change
A notebook costs CZK m, and a pencil costs the same. The ruler costs CZK n. The brush costs CZK 6. Jirka bought 3 notebooks, 2 pencils, a ruler, and a brush. He paid with a fifty-crown note. How much did he get back? - Passenger car and truck
From Kutna Hora left at 11:00 clock a truck at 60 km/h. At 12:30, behind him started the passenger car at an average speed of 80 km/h. At what time and how far from Kutna Hora overtake a passenger car truck? - Two trains meet
From A started at 7:15, the express train at a speed of 85 km/h to B. From B, the passenger train started at 8:30 in the direction of A and at a speed of 55 km/h. The distance A and B are 386 1/4 km. At what time and distance do the two trains meet from B - Cyclist vs car
The cyclist rode out of the city at 18 km/h. One hour 30 minutes behind him started the car and caught up with the cyclist in 50 minutes. How fast was driving the car? Where (what kilometer) from the city car overtook a cyclist? - Tangents construct
The circle k is given k (S; 2.5 cm) and an outer line p. Construct a tangent t of the circle that has a line p angle 60°. How many solutions have the task? - Combinations of sweaters
I have four sweaters: two white, one red, and one green. How many ways can you sort them out? - Birdhouse time
Pupils work in groups of two on technical work in the school to make a birdhouse. If Thomas worked alone, he would make the booth in 4 hours. Richard would do it in 2 hours. If they work together, how many hours will it take them to complete it? - Garden weeding
Dana was supposed to dig a vegetable patch in the garden. She would have carved it in 1.5 hours if she had worked alone. If her sister Hannah were to cut it alone, she would carve it in 0.75 hours. How long would it take them to weed the garden together? - Boots
Master shoemaker has three apprentices. First, do one pair of boots for two days, second for one day, and third for 1.5 days. How long would it take to make a couple of boots if they worked together? - Pool filling time
One pump fills the school pool in 15 hours. The school bought another pump that would fill the pool in 10 hours. What is the latest time to start filling the pool if they want to have it filled at eight o'clock in the morning and use both pumps? - Bath filling
It happens to Dorothy that when filling the bath with water, she forgets to put a plug in the drain. The bath would fill up in 20 minutes if the drain were blocked. A full tub would be emptied through the drain in 30 minutes. How long will it take Dorothy - Novak
Smith needed to dig up three of the same pit in the garden. The first pit was dug father alone for 15 hours. His second dig son helped him, and it did that in six hours. The third pit was dug son himself. How long does it take him? - Cyclist
The cyclist rode two-fifths of the way the first day. On the second day drove 5 km less while traveling three-eighths of the route. How many kilometers does he have to finish the target?
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