Math practice for 13 year olds - page 320 of 413

Number of problems found: 8260

Cancer
Of the 80 people, 50 people were ill with cancer. What percentage of people isn't ill?
Exponent value
Determine the value of f: 0.49^f = 0.7
Exponential equation
Determine m (solve the exponential equation - unknown in the exponent): 0.25 μm = 0.5
Percentage calculation
Determine what 305% of number 98 is.
Similarity coefficient
Determine the similarity coefficient: a) 4.8; 5.6; 8.4 b) 1.44; 1.68; 2.52
Sport probability
Out of 20 boys playing football or handball, 16 boys play football, and 9 boys play handball. Determine the percentage probability that, by randomly selecting a boy, he plays: a) football only; b) only handball c) football and handball
Cablecar
Funicular on Petrin (Prague) was 408 meters long and overcame the difference of 106 meters in altitude. Calculate the angle of the climb.
School reward
There were 560 pupils in the school. They rewarded 8% of all boys and 10% of all girls for excellent results. The directorate stated that teachers rewarded 9% of all pupils. How many boys and how many girls attended the school?
Lighthouse
The man, 180 cm tall, walks along the seafront directly to the lighthouse. The male shadow caused by the beacon light is initially 5.4 meters long. When the man approaches the lighthouse by 90 meters, its shadow is shorter by 3 meters. How tall is the lig
Blueberry collection
Peter, Alex, and Clara collected 112 blueberries. Peter collected two more blueberries than Clara. But Alex collected 34 less than Clara. How many did each of them collect?
Linear system
Solve this linear system (two linear equations with two unknowns): x+y =36 19x+22y=720
Exponent equation
Determine the value of x: 2^x = (2^-3): 2
Exponent value
Find z if 12^z = 1/144
Tetrahedral prism
Calculate the area and volume of a tetrahedral prism that has a base rhomboid shape, and its dimensions are: a = 12 cm, b = 70 mm, v_a = 6 cm, v_h = 1 dm.
Ball probability
We have four red, three blue, six yellow, and two black balls in the bag. Find the probability of pulling the blue or red ball.
Money comparison
Dan has 50% more money than Milos. Jerry has 4 euros more than Miloš. They have a total of 52 euros. Find how much money Daniel, Miloš, and Jerry have.
First man
What is the likelihood of a random event where are five men and seven women will first leave the man?
Geometric progression
Determine the sum of the first three members of GP if q = 2 and a4 = 2.4.
Equation
Solve the equation: 1/2-2/8 = 1/10; Write the result as a decimal number.
Percentage calculation
Determine 120% of numbers 16, 32, 48, and 52.

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