Answer:
The electric field dE due to charge dQ is given as:
dE = (KdQ/r) * r^.
r^ is vector position
r^ = sqrt(x2 + a2). Pythagoras theorem.
K is electrostatic constant. K = 1/4πe(0)
4 is the contestant in the expression
<span>Here we must calculate what percentage of the whole price is represented by the discount amount, which is the difference between the original price and the final one. Hence we have: DiscountedAmount = 440 - 154 = 286. And knowing that 440 constitutes 100% of the price, and 286 constitutes x% of it, we get that x = 286/440 <=> x = 65/100 or 65%. So the answer is D.</span>
