Step 1:
Let $X$ be the random variable denoting the number of accidents involving taxi drivers in a year.
$X\sim P(3)$
$P(X=x)=\large\frac{e{-3}3^x}{x!}\qquad$$ x=0,1,2........$
Step 2:
Probability that a taxi driver is involved in more than 3 accidents in a year.
$P(X > 3)=1-P(X\leq 3)$
$\qquad\quad\;\;=1-[P(X=0)+P(X=1)+P(X=2)+P(X=1)]$
$\qquad\quad\;\;=1-e^{-3}[\large\frac{3^0}{0!}+\frac{3^1}{1!}+\frac{3^2}{2!}+\frac{3^3}{3!}$
$\qquad\quad\;\;=1-0.0498[1+3+\large\frac{9}{2}+\frac{9}{2}]$
$\qquad\quad\;\;=1-0.0498\times 13$
$\qquad\quad\;\;=1-0.6474$
$\qquad\quad\;\;=0.3526$
No of taxi drivers out of 1000 who are expect ion to be involved in more than 3 accidents =1000$\times 0.3526=353$(approx)