Discussion
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- Question
- In a class, 50 students play cricket, 20 students play football and 10 play both cricket and football. How many play at least one of these two games?
Options- A. 60
- B. 45
- C. 55
- D. 65
- Correct Answer
- 60
ExplanationGiven: n(C) = 50, n(F) = 20, n(C ? F) = 10.
Number of students playing at least one of these two games = n (C ? F) = n (C) + n (F) ? n (C ? F)
= 50 + 20 ? 10 = 60. - 1. Which of the following pairs of sets are comparable?
Options- A. A = {1, 3, 5}, and B = {3, 2, 5, 6}
- B. A = {x: x ? N and x ? 10} and B = {1, 2, 3,?, 10, 11}
- C. A = {1, 2, 3, {4, 5}}, and B = {1, 2, 3, 4, 5}.
- D. None of these Discuss
- 2. Write down the power set of A = {8, 9}.
Options- A. {?, {8}, {9}, {8, 9}}
- B. {?, {8}, {9}}
- C. {?, {8}, {9}, {8, 9}}
- D. None of these Discuss
- 3. If A = {1, 2, 3, 4, 5} and B = {2, 4, 6} then what is the value of A - B?
Options- A. {2, 3, 5}
- B. {1, 3, 5}
- C. {2, 3, 6}
- D. {1, 4, 5} Discuss
- 4. In an examination, 30% of the total students failed in Hindi, 45% failed in English and 20% failed in both the subjects. Find the percentage of those who passed in both the subjects.
Options- A. 35.7%
- B. 35%
- C. 40%
- D. 45% Discuss
- 5. There are 80 families in a small extension area. 20 per cent of these families own a car each. 50 per cent of the remaining families own a motor cycle each. How many families in that extension do not own any vehicle?
Options- A. 30
- B. 32
- C. 23
- D. 36 Discuss
- 6. Which of the following sets is finite?
Options- A. {x: x ? N and x is a prime number}
- B. {x: x is a quadrilateral on a plane}
- C. {x: x ? N and x2 ? 25 ? 0}
- D. {x: x ? N and x is a multiple of 3} Discuss
- 7. Which of the following sets is infinite?
Options- A. {x: x is a prime number, x is even}
- B. Set of all river in India
- C. Set of all concentric circles
- D. None of above Discuss
- 8. Find the cardinal number of the following set :
{x : x is a letter of the word 'ASSASSINATION'}
Options- A. 4
- B. 6
- C. 8
- D. 2 Discuss
- 9. Which of the following statements is false for the sets A, B and C, where:
A = {x | x is letter of the word 'BOWL'}
B = {x | x is a letter of the word 'ELBOW'}
C = {x | x is a letter of the word 'BELLOW'}
Options- A. A ? B
- B. B ? C
- C. B = C
- D. B is a proper subset of C. Discuss
- 10. Which of the following pairs of sets are disjoint?
(i) {1, 2, 3, 4 } and { x : x is a natural number and 4 ? x ? 6 }
(ii) { a, e, i, o, u } and { c, d, e, f }
(iii) { x : x is an even integer } and { x : x is an odd integer }.
Options- A. (i)
- B. (ii)
- C. (iii)
- D. None of these Discuss
Sets and Functions problems
Search Results
Correct Answer: A = {x: x ? N and x ? 10} and B = {1, 2, 3,?, 10, 11}
Explanation:
(a) 1? A but 1? B and 6 ? B but 6 ? A.
? A and B are not comparable.
(b) A = {x: x ? N and x ? 10} = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} B = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}
Clearly, A ? B ? A and B are comparable.
(c) {4, 5} ? A but {4, 5} ? B and 4 ? B but 4 ? A.
? A and B are not comparable.
Correct Answer: {?, {8}, {9}, {8, 9}}
Explanation:
NA
Correct Answer: {1, 3, 5}
Explanation:
A new set having those elements which are in A but not in B is said to be the difference of sets A and B and it is denoted by A ? B.
Given that in question, A = {1, 2, 3, 4, 5} and B = {2, 4, 6}
So the numbers which are in A and but not in B = {1, 3, 5}
? A ? B = {1, 3, 5}
Correct Answer: 45%
Explanation:
Let the number of students be 100. Number of students who failed in Hindi is 30%.
n(H) = 30
Number of students who failed in English is 45%.
? n(E) = 45
Number of students who failed in both the subjects is 20%. n(H ? E) = 20
Applying the rule,
n(H ? E) = n(H) + n(E) - n(H ? E)
= 30 + 45 - 20 = 55
Percentage of students who failed in Hindi or English or both the subjects = 55%
Number of students who passed in both the subjects = 100 - 55 = 45%
Correct Answer: 32
Explanation:
Given in the question,
20% of 80 = 20 * 80 / 100 = 16
Remaining 50%
= (80 ? 16) × 50 / 100 = 32
No. of families not owning any vehicle
= 80 ? (32 + 16) = 80 ? 48 = 32
Correct Answer: {x: x ? N and x2 ? 25 ? 0}
Explanation:
NA
Correct Answer: Set of all concentric circles
Explanation:
NA
Correct Answer: 6
Explanation:
NA
Correct Answer: B is a proper subset of C.
Explanation:
NA
Correct Answer: (iii)
Explanation:
(a) {x: x is a natural number and 4 ? x ? 6} = {4, 5, 6}. Now, {1, 2, 3, 4} and {4, 5, 6} have one element 4 common. Therefore, the given two sets are not disjoint.
(b) The sets {a, e, i, o, u} and {c, d, e, f} have one element e as common. Then, the given two sets are not disjoint.
(c) The sets {x: x is an even integer} and {x: x is an odd integer} have no element as common and therefore they are disjoint sets.
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