Final answer:
The cross-rate for ZAR/HKD cannot be determined without clear base rates for ZAR to USD and HKD to USD. The data provided is insufficient for calculating an exact cross-rate.
Step-by-step explanation:
To determine the spot cross-rate for ZAR/HKD, we need to have the exchange rates for ZAR to USD and HKD to USD. However, in this context, you have provided two lists that seem to represent the changes in currency values over time without specifically mentioning the base currency. To accurately calculate the cross-rate, an exchange rate against a common base currency such as USD is typically used for both currencies in question. Nevertheless, if we assume that the first list corresponds to ZAR/USD and the second corresponds to HKD/USD, then the average of the rates provided could be used as a rough estimate to calculate the spot cross-rate. However, this method would not be precise without clear base rates. Without additional information, providing the exact cross-rate for ZAR/HKD is not possible.