Sets + reason - practice problems - page 2 of 5
Number of problems found: 94
- Following 34291
The following holds for two non-empty sets, A and B: A ∪ B has 16 elements, A ∩ B has 11 elements, and the set A - B is empty. How many elements does set B-A to have? - Venn diagram
University students choose a foreign language for the 1st year. Of the 120 enrolled students, 75 chose English, 65 German, and 40 both English and German. Using the Venn diagram, determine: - how many of the enrolled students chose English only - how many - Language courses
Of the company's 60 employees, 28 attend an English course, 17 take a German course, and 20 do not attend any of these courses. How many employees attend both courses? - Intersections 26781
A rectangular grid consists of two mutually perpendicular systems of parallel lines with a distance of 2. We throw a circle with a diameter of 1 on this plane. Calculate the probability that this circle: a) overlaps one of the straight lines; b) do any of
- Defective 23221
The factory sets a standard that 2% of products may be defective. Last week, out of 1,250 products, 32 were defective. How many defective products were the standard exceeded? - Double probability
The probability of success of the planned action is 60%. What is the probability that we will achieve success at least once if this action is repeated twice? - Alarm systems
What is the probability that at least one alarm system will signal the theft of a motor vehicle when the efficiency of the first system is 90% and of the independent second system 80%? - Fall sum or same
Find the probability that if you roll two dice, it will fall the sum of 10, or the same number will fall on both dice. - Return 15193
Fiona sets off from the tower after Shrek at 9:10 at a speed of 6 km/h. Shrek starts to meet her from the swamp at 9:50 at a speed of 4 km/h. At 10:50, they meet and return back to the swamp at a speed of 4 km/h. What time does he arrive at the swamp?
- Christmas or Easter
Please calculate this example by the Venn equation. They asked 73 students whether they liked Christmas or Easter. Thirty-four of them like one of the holidays. 39 loves Easter. There are twice as many students who wish for both holidays as those who only - Brothers and sisters
There are 35 children in the class; 23 have a brother, and 27 have a sister. When five children in the class have no brother or sister, how many children have both a brother and a sister? - Glasses
There are 36 pupils in the class. Nine girls wear glasses. Boys with glasses are five less than girls without glasses. Boys without glasses are two times more than girls without glasses. How many boys and how many girls? - School trip
On a school trip, 17 of the 28 children bought ice cream or chocolate in a candy store. Twelve children bought chocolate, and nine children bought ice cream. How many children bought ice cream and chocolate? How many children did not buy ice cream? How ma - Three excursions
Each pupil of the 9A class attended at least one of the three excursions. There could always be 15 pupils on each excursion. Seven participants of the first excursion also participated in the second, 8 participants of the first excursion, and 5 participan
- Four-digit 10261
Roman likes magic and math. Last time he conjured three- or four-digit numbers like this: • created two new numbers from the given number by dividing it between digits in the place of hundreds and tens (e.g., from the number 581, he would get 5 and 81), • - Sufficient 9391
In Kocourkov, they use coins with only two values expressed in Kocourkov crowns by positive integers. With a sufficient number of such coins, it is possible to pay any integer amount greater than 53 cats’ crowns accurately and without return. However, we - Justification 8468
The natural number n has at least 73 two-digit divisors. Prove that one of them is the number 60. Also, give an example of the number n, which has exactly 73 double-digit divisors, including a proper justification. - Entertainment 8353
Twenty-two pupils attend class 4A. Of these, 12 pupils subscribe to a research magazine, 5 pupils subscribe to an entertainment magazine, and 8 pupils do not subscribe to any of these magazines. How many pupils subscribe to both magazines? - Pupils
There are 27 pupils in the classroom. They can swim 21 and ski nine pupils. Neither swim nor ski three pupils. How many pupils can swim and ski?
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