The export business in China is growing. Uncle George, who has just returned from a trade expo in Shanghai, has informed you that the port authority of Ningbo expects the demand to reach the same level as Shanghai. The port authority of Ningbo is now deciding how to change its system to accommodate this surge in demand. They have two options, (a) to retire their existing x-ray machine and buy an x-ray machine similar to the one used by the Shanghai port, or (b) to buy another x-ray machine similar to the one they already own and therefore operate the system with two similar machines. Both the options will cost the port authority of Ningbo the same. Purely from the perspective of reducing lead-time, is (a) or (b) better for you? Please show your detailed analysis.