12 ÷ 3= 4. Hope this helps. ;)
Answer:
Height = 21.78 ft
Step-by-step explanation:
Tan θ = opposite / Adjacent
tan 40 = opposite / 20
where opposite is the part of the traffic light
0.839 × 20 = opposite
opposite = 16.78 ft
Now the total height of traffic light = 16.78 ft +5 ft
Total Height = 21.78 ft
The probability density function (pdf) is;
f(x)=
for a ≤ x ≤ b.
while the mean is given as 
And the standard deviation given as 