Answer:2 ft/s
Explanation:
Given
Length of Pole is 9 ft
Length of Joe is 3 ft
Joe walks away from Pole at the rate 4 ft/s
Let Joe is x m away from Pole so its shadow length is x'
From Similar triangle concept

3x'=x+x'
x=2x'
and it is given 
Differentiating



Answer: A
Explanation:
Parallel circuit. The source current is three times the current of a single bulb
A and c should be the answer
The first shell has 2 in and the second shell has 8 in therefore ypuvwont need to add anymore :-) so the answer is 0