Answer
0.523
Work Step by Step
We have $p=0.173, n=120$
Check $np=20.76\gt5, n(1-p)=99,24\gt5$
We will use normal approximation to the binomial distribution.
$\mu=np=20.76, \sigma=\sqrt {np(1-p)}=4.14$
$X1=20.5, X2=34.5, z1=\frac{20.5-20.76}{4.14}=-0.06, z2=\frac{34.5-20.76}{4.14}=3.32$
The probability between z1 and z2 is 0.523