The least positive integer $n$ for which $\sqrt{n+1}-\sqrt{n-1} < 0.2$ is

Find the set of all values of $x$ satisfying $\frac{x^4 - 4x^3 + 3x^2}{(x^2 - 4)(x^2 - 7x + 10)} \ge 0$.

Eleven apples are distributed among a girl and a boy. Then,which one of the following statements is true?

The region represented by the inequations $2x + 3y \leqslant 18$,$x + y \geqslant 10$,$x \geqslant 0$,$y \geqslant 0$ is

$\left\{x \in R: \frac{14 x}{x+1}-\frac{9 x-30}{x-4} < 0\right\}$ is equal to

The $IQ$ of a person is given by the formula $IQ = \frac{MA}{CA} \times 100$,where $MA$ is mental age and $CA$ is chronological age. If $80 \leq IQ \leq 140$ for a group of $12$ years old children,find the range of their mental age.