Table:
|  | Weighted Average Useful Life | April 4, 2016 |
| --- | --- | --- |
|  | (in years) | (in millions) |
| Core and developed technology | 11 | $1,075.0 |
| In-process research and development | — | 140.7 |
| Customer-related | 6 | 630.6 |
| Backlog | 1 | 40.3 |
| Other | 5 | 1.8 |
| Total purchased intangible assets |  | $1,888.4 |
Paragraphs:
Purchased Intangible Assets
Purchased intangible assets include core and developed technology, in-process research and development, customer-related intangibles, acquisition-date backlog and other intangible assets. The estimated fair values of the core and developed technology and in-process research and development were determined based on the present value of the expected cash flows to be generated by the respective existing technology or future technology. The core and developed technology intangible assets are being amortized in a manner based on the expected cash flows used in the initial determination of fair value. In-process research and development is capitalized until such time as the related projects are completed or abandoned at which time the capitalized amounts will begin to be amortized or written off. Customer-related intangible assets consist of Atmel's contractual relationships and customer loyalty related to its distributor and end-customer relationships, and the fair values of the customerrelated intangibles were determined based on Atmel's projected revenues. An analysis of expected attrition and revenue growth for existing customers was prepared from Atmel's historical customer information. Customer relationships are being amortized in a manner based on the estimated cash flows associated with the existing customers and anticipated retention rates. Backlog relates to the value of orders not yet shipped by Atmel at the acquisition date, and the fair values were based on the estimated profit associated with those orders. Backlog related assets had a one year useful life and were being amortized on a straight line basis over that period. The total weighted average amortization period of intangible assets acquired as a result of the Atmel transaction is 9 years. Amortization expense associated with acquired intangible assets is not deductible for tax purposes. Thus, approximately $178.1 million was established as a net deferred tax liability for the future amortization of the intangible assets.
Question:
How was the stimated fair values of the core and developed technology and in-process research and development determined?
Answer: based on the present value of the expected cash flows to be generated by the respective existing technology or future technology.