A nylon string has a linear density of 7.2g/m and is under a tension of 150N. The fixed supports are 90cm apart. The string is oscillating in the standing wave pattern. Find a)speed b)wavelength c) frequency

v=sqr(F/u(linear density)
v=sqrt(150N/7.2g/m)
= 4.56m/s

b) wavelength = 2L/3
= .6
The formular is =2L/n
n= nodes. The pictures shows three nodes in the standing wave pattern.

c) v= wavelength * frequency
4.56=.6 *f
f=7.6 Hz

Shouldn't linear density be changed to kg/m when determining velocity?
Wavelength should be twice the 90cm, shouldn't it? The end points determine the nodes, and between nodes it should be 1/2 wavelength.
wavelength= 2(.9m) I don't know why you chose n=3, I would have thought n=1 for the fundamental.