Percentages + reason - math problems
After the fifth-grade class left 20% of students. In the seventh grade were added 2 pupils, in the eighth 1 pupil, in the ninth, the number has not changed, but it is now tenth students less than it was in the fifth grade. How many pupils are in the 9th.
- Harvest time
Grandma and granddaughter Julka reap currants in 15 hours of working together. Julka herself would have currants 10 days after 6 hours of work a day. Find by what percentage the grandma's harvest time was shortened when the granddaughter was involved in c
- Before yesterday
He merchant adds a sale sign in his shop window to the showed pair of shoes in the morning: "Today by p% cheaper than yesterday. " After a while, however, he decided that the sign saying: "Today 62.5% cheaper than the day before yesterday". Determine the n
- Folding table
The folding kitchen table has a rectangular shape with an area of 168dm2 (side and is 14 dm long). If necessary, it can be enlarged by sliding two semi-circular plates (at sides b). How much percent will the table area increase? The result round to one-hun
In January, 2 liters of lemonade were sold for CZK 24, while in February, 2.5 liters of lemonade sold at same price. How much percent was 1 liter of lemonade cheaper in February than in January?
Fresh mushrooms contain 88% water, dried 14% water. How many kilograms of fresh mushrooms should be collected to get 3 kg of dried?
- Geography tests
On three 150-point geography tests, you earned grades of 88%, 94%, and 90%. The final test is worth 250 points. What percent do you need on the final to earn 93% of the total points on all tests?
- Left handed
It is known that 25% of the population is left-handed. What is the probability that there is a maximum of three left-handers at a seminar where there are 30 participants?
- Utopia Island
A probability of disease A on the island of Utopia is 40%. A probability of occurrence among the men of this island, which make up 60% of all the population (the rest are women), is 50%. What is the probability of occurrence of A disease among women on Uto
- Math test
Obelix filled a mathematical test in which he answered 25 questions. For every correct answer, he received 5 points, for each bad answer he had 3 points deducted. Obelix gained 36% of all points in the test. How many questions did he solve correctly?
- Bdf tablet
Detective Harry Thomson has come across a surprising mystery. As part of the weekend's action, the tablet he looked for dropped by 30%. He also recommended this bargain to his friend. However, it came to the shop on Monday, and the tablet was 30% more expe
- Cut trees
There are 1,200 trees in the grove, of which 55 percent are deciduous, the remaining coniferous. Workers cut down 35 percent a) trees, b) deciduous trees, c) coniferous trees. How many trees now have this grove?
- Four numbers
The first number is 50% second, the second number is 40% third, the third number is 20% of the fourth. The sum is 396. What are the numbers?
- Profit per kilo
The trader sells apples at a profit of 20% per kilogram. Today, he decided to reduce the price of apples by 10%. How much profit does the trader have today?
- On a farm
On a farm, there are 90 rabbits, 700 sheep, 300 cattle and 500 pigs. What percentage of the total number of animals are rabbits?
The dress was discounted by CZK 115, which was 12% of the original price. What is the cost of the dress after the discount?
- Associative law multiplication
In a warehouse, you obtain a 20% discount but you must pay a 15% sales tax. Which would you prefer to have calculated first: discount or tax? Explain. (result write as: 1 = first discount, 2 = first tax, 3 = no matter what first)
- Sum on dice
We have two dice. What is the greater likelihood of fall a total sum 7 or 8 ? (write 7, 8 or 0 if the probabilities are the same)?
- Kaufland sales-off
As a rule the goods to the approaching end consumption in Kaufland three days before the end of the consumption to 30% off and one day before the end of the consumption to 50% discounts. Sometimes however the seller has been mistaken and the second discoun
- Three reds
What is the probability that when choosing 3 carats from seven carats, all 3 reds will be red?
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