Given:
The power generated by an electrical circuit (in watts) as a function of its current x (in amperes) is modeled by

To find:
The current which will produce the maximum power.
Solution:
We have,


Differentiate with respect to x.

...(i)
To find the extreme point equate P'(x)=0.


Divide both sides by -30.

Differentiate (i) with respect to x.

(Maximum)
It means, the given function is maximum at x=4.
Therefore, the current of 4 amperes will produce the maximum power.
I think you meant it to be not repeating 3 times so
You do 192/3 is 60*3= 180 leaving you with 12 which is 4*3. So 64 is A
Then it’s 300/5 which is 60
455/7. So first see, if I multiply 7 by 60 is it over or under. If it’s over then B is the least and if it is less then C is the least. So 7 *60 is 420
C Being greater, b costs least per night
If you are given he has blond hair, so the total probability will be 35%. And among them, he needs to have blue eyes, its probability is 14% among the 35%. So the final probability is 14%/35%=40%.