Apple Inc. is planning to invest in research and development (R&D) projects for the development of its next-generation iPhone. The company expects to incur R&D expenses of $1 billion over the next two years. If the projects are successful, Apple anticipates generating additional annual revenues of $5 billion for the next five years. However, there's a 20% probability of the projects failing, resulting in no additional revenue. Calculate the expected net present value (NPV) of the R&D projects for Apple Inc., assuming a discount rate of 10%.