When a stationary wave is formed,what is its frequency compared to the individual waves that form it?

$A$ string is vibrating in its fifth overtone between two rigid supports $2.4 \ m$ apart. The distance between successive node and antinode is (in $m$)

For a stationary wave represented by the equation $y = 0.15 \sin(5x) \cos(300t) \, \text{m}$,what is the wavelength of the wave (in $, \text{m}$)?

The stationary wave produced on a string is represented by the equation $y = 5 \cos (\pi x / 3) \sin (40 \pi t)$. Where $x$ and $y$ are in $cm$ and $t$ is in seconds. The distance between consecutive nodes is .... $cm$.

$A$ wave of frequency $100 \, Hz$ is sent along a string towards a fixed end. When this wave travels back after reflection,a node is formed at a distance of $10 \, cm$ from the fixed end of the string. The speed of the incident (and reflected) wave is .... $m/s$.

The given diagram shows a detector placed between a transmitter of sound waves and a metal plate. At three adjacent points,$R, S$ and $T$,the meter shows zero intensity. Which of the following is the frequency of the emitted wave in $Hz$? (Take the velocity of sound as $v = 300 \, m/s$)