Let $A = \{a, b, c\}$ and $B = \{1, 2, 3, 4\}$. Then the number of elements in the set $C = \{f : A \rightarrow B \mid 2 \in f(A) \text{ and } f \text{ is not one-one}\}$ is

In a group of $1000$ people,there are $750$ people who can speak Hindi and $400$ who can speak English. How many can speak Hindi only?

Let $X = \{ 1, 2, 3, 4, 5 \}$ and $Y = \{ 1, 3, 5, 7, 9 \}$. Which of the following is/are relations from $X$ to $Y$?

Which of the following is the empty set?

If the sets $A$ and $B$ are defined as $A = \{ (x, y) : y = \frac{1}{x}, x \in R, x \neq 0 \}$ and $B = \{ (x, y) : y = -x, x \in R \}$,then:

In a survey of a town,it was found that $65 \%$ of the people surveyed watch the news on $T.V.$,$40 \%$ read a newspaper,and $25 \%$ read a newspaper and watch the news on $T.V.$ What percent of the people surveyed neither watch the news on $T.V.$ nor read a newspaper?