Maths practice for 14 year olds - page 313 of 382

Number of problems found: 7626

Concentration
How many grams of 65% and 50% acid are to be mixed to give 240 g of acid with a concentration of 60%?
Hydrochloric acid
Determine the concentration of which must have a solution of hydrochloric acid that mixes 10 l of the solution with 8 liters of 26% solution to get the solution with a concentration of 50%.
Acid solution
By adding 250 grams of a 96% sulfuric acid solution to its 3% solution, we changed its initial concentration to 25%. How many grams of 3% of the acid were used for dilution?
Product of three
The product of 3 numbers is 42. The first is 1.5 times larger than the second number, and the third is 3.5 times larger than the second number. What numbers are these?
Water mixing
Find how many liters of water at 80 °C and 20 °C need to mix to get 30 liters at 60 °C.
Tree storm
In the orchard, there were 46 more apple trees than pears. The storm upset a quarter of apple trees and seven pears; however, there were still 80 trees left. How many were apple trees, and how many pears were in the garden?
Apple baskets
How many apples are in the fifth and eighth baskets if there are five apples in the first and 11 more apples in the next than in the previous one?
Water mixing - tub
The tank has water with a volume of 300 liters and a temperature of 10 °C. Add water at a temperature of 90 °C until a temperature of 30 °C is reached. How many liters of warmer water do I need to add?
Concrete block
Determine the volume of the concrete block whose one edge of the base is 3 meters long, the body diagonal is 13 meters, and the height is 12 meters.
Distilled water
Seawater contains 5% salt. How much distilled water should be poured into 40 kg of seawater so that the salt content is 2%? How many kilograms of 2% of seawater do we get?
Number difference
The difference between the two numbers is 4/3. If you know that the first number is 50% larger than the second number, specify both numbers.
Water temperatures
To 25 liters of water at 50 °C, we add 15 liters of water at a different temperature. How many °C should the water be colder than 50 °C so that 40 liters of the water obtained has a temperature of 42.5 °C?
Acid solution concentration
Calculate the concentration of the solution prepared from 6 kg of 95% sulfuric acid solution and 24 kilograms of 10% sulfuric acid solution.
Formic acid mixture
How many liters of 60% and 80% formic acid do we have to mix to get 80 liters of this acid with a concentration of 65%?
Candy
The price for 1 kg of more expensive candy is 125 CZK. The price for 1 kg of cheaper candy is 100 CZK. We make two different blends of candy. And now. The second blend contains 2 kilograms of more expensive candy and several kg of cheaper candy. The price
Solution dilution
1.5 kg of a 20% NaCl solution should be diluted to a 10% solution with water. How much water will we need, and how many kilograms of diluted solution will we get?
Alcohol
How many cubic centimeters of 96% alcohol is needed to obtain 0.75 liters of 40% alcohol?
Alcohol mixing
How many liters of 80% alcohol need to be mixed with 4 liters of 40% alcohol to get 70% alcohol? How many liters of 70% solution do we get?
Two numbers sum
The sum of the two numbers is 52.5. The first number makes up 75% of the second number. Specify both numbers.
Solution
What amount of 80% solution and water is needed to mix to obtain two liters of 60% solution of this mixture?

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