on the way to work a guy must pass through $10$ traffic lights suppose that in the long run he encounters a red light at $40$% of these signals and whether any particular signal is red is independent of whether any other one is red
On what proprotion of days will our friend encounter at most two red lights?
$40$% of 10 is 4, so I take lambda = 4
"At most two" means 0 red lights + 1 red light + 2 red lights.
So this must mean that we can use a poisson cdf function with lambda = 4 and $x$ = 2 which in the poisson distribution table is 0.2381
However, the correct answer is actually $0.167$
What am I missing?