Chapter 6 - Section 6.3 - Assess Your Understanding - Vocabulary and Skill Building - Page 351: 7b

$P(x<6)=0.616$

$P(x<6)=P(0)+P(1)+P(2)+P(3)+P(4)+P(5)=\frac{5^{0}}{0!}e^{-5}+\frac{5^{1}}{1!}e^{-5}+\frac{5^{2}}{2!}e^{-5}+\frac{5^{3}}{3!}e^{-5}+\frac{5^{4}}{4!}e^{-5}+\frac{5^{5}}{5!}e^{-5}=\frac{1}{1}e^{-5}+\frac{5}{1}e^{-5}+\frac{25}{2}e^{-5}+\frac{125}{6}e^{-5}+\frac{625}{24}e^{-5}+\frac{3125}{120}e^{-5}=0.616$