Maths practice for 14 year olds - page 139 of 370

Number of problems found: 7388

Solution 38451
Prepare 2 liters (kg) of a 3% salt solution in water.
Participants
Of the 48 participants, six were women, fewer than men, and 24 were children, less than all adults. Calculate the percentage of all participants on the tour who are children.
Solution 38411
Prepare 250g of a 30% solution of hydrogen peroxide in water.
Salicylic 38401
Prepare 600 g of an 8% solution of salicylic acid.
Solution 38391
Prepare 100g of a 15% blue rock solution.
Three-digit 38371
How many odd three-digit numbers can you make of the five cards with the numbers 1, 2, 3, 5, and 6?
Minutes 38331
Two planes took off from Prague at one point. The first is flying north at a speed of 420 km/h, and the second is flying east at a speed of 560 km/h. How far apart will they be as the crow flies in 25 minutes of flight?
Regular 4-sided pyramid
Find the area (surface area) of a regular 4-sided pyramid if its height is 20 m and the wall height is 23 m.
Clock's 38311
How far apart are the tips of the clock's hands in 3 hours if the larger hand is 124 mm long and the smaller 75 mm?
Bricklayer 38291
A bricklayer will lay 12 m³ of brickwork in 4 days if he works 7 hours a day. How many days will he lay 51 m³ of masonry if he works 8.5 hours daily?
Rotary motion
Find the orbital time, rotational frequency, and angular rate of the second and minute hands on the watch.
Difference 38253
The blue coat, which costs CZK 1,200, has a price 40% lower than the red coat. What is the price difference between the two coats?
Isosceles + prism
Calculate the volume of the perpendicular prism if its height is 17.5 cm and the base is an isosceles triangle with a base length of 5.8 cm and an arm's length of 3.7 cm.
Lions
If eight lions are 40%, how many would 75% be?
Arm and base
The isosceles triangle has a circumference of 46 cm. If the arm is 5 cm longer than the base, calculate its area.
Motorbike circuit
On a 2,550 m long circuit, two motorcycles go at such speeds that they meet every minute if they go against each other and run every 5 minutes if they go in the same direction. Find their speeds.
Possibilities 38143
If residents of MISSISSIPPI state have to use all the letters to choose their country's name, how many possibilities do they have?
Different 38123
How many ways can we put seven different books on the shelf?
Starting 38113
How many ways can we put 19 students in a row when starting a gym?
Repeated 38103
How many 5-digit numbers can we assemble from the numbers 2,3,4,5,6,7,8,9 if each digit can be repeated only once?

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