Correct Answer: 587.5

Solution : The discount of the article A1 = 650 – 550 = 100.
The discount of the article A2 = 500 – 350 = 150.
The discount of the article A3 = 550 – 400 = 150.
The discount of the article A4 = 350 – 300 = 50.
J1 = The value of the average discount of articles A1, A2, A3, and A4
= $\frac{100+150+150+50}{4}=\frac{450}{4}=112.5$.
The difference between the marked price and the selling price of articles A5 = 750 – 550 = 200.
The difference between the marked price and the selling price of articles A6 = 250 – 200 = 50.
J2 = The difference between the marked price and the selling price of all articles
= 100 + 150 + 150 + 50 + 200 + 50 = 700.
The value of J2 – J1 = 700 – 112.5 = 587.5.
Hence, the correct answer is 587.5.