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Question

The following questions are based on the information given below:

All the 3200 students of a college in a city know at least one of the three languages English, Telugu and Hindi. 2400 know English, 1700 know Telugu, 800 know Hindi, 1000 know English and Telugu, 500 speak English and Hindi, 300 speak Telugu and Hindi and only 100 know all three languages.

How many do not know any of the three languages?

A. 0

B. 1

C. 10

D. 15

The correct answer is

A

Understanding the Language Knowledge Problem

The question provides data about the language knowledge of 3200 students in a college. The languages are English, Telugu, and Hindi. We are given the number of students who know each language individually and in combinations.

However, the most crucial piece of information for this specific question is stated at the very beginning:

  • "All the 3200 students of a college in a city know at least one of the three languages English, Telugu and Hindi."

Total Students and the Key Condition

The total number of students in the college is 3200.

The problem statement explicitly says that every single student among these 3200 knows "at least one" of the three languages (English, Telugu, or Hindi).

Knowing "at least one" language means a student knows either one language, or two languages, or all three languages.

Finding Students Who Know None

The question asks: "How many do not know any of the three languages?"

Based on the condition provided, "All the 3200 students... know at least one of the three languages", there are no students who know zero languages.

If every student knows at least one language, then the number of students who do not know any language must be 0.

The other numbers provided in the question (like 2400 know English, 1000 know English and Telugu, etc.) are useful for other types of set theory problems (e.g., finding how many know exactly one language), but they are not needed to answer this specific question because the introductory statement directly addresses the condition of knowing 'none'.

Conclusion on Language Knowledge

Since the problem states that all 3200 students know at least one language, the number of students who do not know any of the three languages is zero.

Therefore, the count of students who do not know any of the three languages is 0.

Revision Table: Key Concepts

Concept Explanation
Total Population The total number of individuals in the set (here, 3200 students).
"At Least One" Condition This means an individual belongs to at least one of the specified categories (here, knows at least one language). Mathematically, this corresponds to the union of the sets ($E \cup T \cup H$).
"None" Condition This means an individual belongs to none of the specified categories. This corresponds to individuals outside the union of the sets.

Additional Information: Set Theory Basics

This type of problem involves basic set theory, specifically dealing with the number of elements in sets and their unions and intersections. The information about knowing specific combinations of languages (English and Telugu, Telugu and Hindi, etc.) is typically used with the Principle of Inclusion-Exclusion to find the total number of students who know at least one language when that number isn't directly given.

The Principle of Inclusion-Exclusion for three sets (E, T, H) is:

\(|E \cup T \cup H| = |E| + |T| + |H| - |E \cap T| - |T \cap H| - |E \cap H| + |E \cap T \cap H|\)

In this problem, we are told that all 3200 students know at least one language. This means the total number of students is equal to the number of students who know at least one language, i.e., \(|E \cup T \cup H| = 3200\). If we were to calculate \(|E \cup T \cup H|\) using the given numbers:

  • \(|E| = 2400\)
  • \(|T| = 1700\)
  • \(|H| = 800\)
  • \(|E \cap T| = 1000\)
  • \(|E \cap H| = 500\)
  • \(|T \cap H| = 300\)
  • \(|E \cap T \cap H| = 100\)

Using the formula:

\(|E \cup T \cup H| = 2400 + 1700 + 800 - 1000 - 500 - 300 + 100\)

\(|E \cup T \cup H| = 4900 - 1800 + 100\)

\(|E \cup T \cup H| = 3100 + 100\)

\(|E \cup T \cup H| = 3200\)

This calculation confirms that the number of students knowing at least one language is indeed 3200, which matches the total number of students given. This reinforces the initial statement that everyone knows at least one language, leaving no students who know none.

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Important Questions from Caselet DI

  1. How many students like only one vegetable?

    A. 60

    B. 61

    C. 65

    D. 71

  2. The difference between the people who like carrot and cauliflower is

    A. 6

    B. 18

    C. 16

    D. 4
  3. What is the percentage of students that do not like cabbage?

    A. 16

    B. 32

    C. 24

    D. 68

  4. How many know only one of the three languages?

    A. 1600

    B. 900

    C. 300

    D. 100

  5. How many know only Hindi?

    A. 200

    B. 400

    C. 100

    D. 800

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