## Elementary Statistics: A Step-by-Step Approach with Formula Card 9th Edition

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