Question

Staff employed in a UNESCO office in Paris are represented by four intersecting circles, one each for people who can read and write English, French, Spanish and Russian, as shown in the diagram above.
Given: \(a = 40\), \(c = 2a\), \(e = \frac{1}{2}a\), \(g = 2e\).
How many people know only Spanish?

• A. 10
• B. 20
• C. 40
• D. 60

Hint:

Only-Spanish is the region exclusive to the Spanish circle, given directly as e = (1/2)a.

Answer 1

The Correct Option is B

Step 1: Identify which region represents "only Spanish".
In the four-circle diagram, the Spanish circle is at the bottom right. The region labelled "e" is the part of the Spanish circle that does not overlap with the Russian, English or French circles, so region e represents people who know only Spanish.

Step 2: Apply the given relation.
We are given \(a = 40\) (people who know only Russian) and \(e = \frac{1}{2}a\) (people who know only Spanish is half of people who know only Russian).
So \(e = \frac{1}{2} \times 40 = 20\).

Final Answer:
The number of people who know only Spanish is 20. \[ \boxed{20} \]