venn-diagram -

3 votes

There are $16$ teachers who can teach Thermodynamics $\text{(TD)}$, $11$ who can teach Electrical Sciences $\text{(ES)}$, and $5$ who can teach both $\text{TD}$ and Engineering Mechanics $\text{(EM)}$. There are a total of $40$ teachers. $6$ cannot teach any of the three subjects, i.e. $\text{EM, ES}$ or $\text{TD}$. $6$ can teach only $\text{ES}$. $4$ can teach all three subjects, i.e. $\text{EM, ES}$ and $\text{TD}$. $4$ can teach $\text{ES}$ and $\text{TD}$. How many can teach both $\text{ES}$ and $\text{EM}$ but not $\text{TD}$?

- $1$
- $2$
- $3$
- $4$

7 votes

Best answer

A total of 11 teachers can teach ES.

Now the question says, **6** teachers can teach **only ES** so the number of teachers teaching both ES and EM has to be less than or equal to $(11-6)$ i.e., **5**.

Also, **4** teachers can teach **all three subjects**.

The question asks for the number of teachers who **can teach ES and EM but not TD**.

Subtract $4$ from the $5$ derived earlier.

**Ans 1.** Option A