Four waves are to be sent along the same string, in the same direction:

y$1($x$,$ t$)=(4\mathrm{.}00$ mm$)$ sin$(2$x $-404$t $+0\mathrm{.}37$$)$

Y$2($x$,$ t$)=(4\mathrm{.}00$ mm$)$ sin$(2$x $-404$t $+0\mathrm{.}71$$)$

y$3($x$,$ t$)=(4\mathrm{.}00$ mm$)$ sin$(2$x $-404$t $+1\mathrm{.}37$$)$

y$4($x$,$ t$)=(4\mathrm{.}00$ mm$)$ sin$(2$x $-404$t $+1\mathrm{.}71$$).$