After market close on Tuesday, Wall Street will lend an ear as the world's most valuable company reports fiscal 2015 fourth-quarter results. While investors will undoubtedly tune into to Apple's (NASDAQ:AAPL) reported iPhone sales, revenue, and earnings-per-share figures, many will also be listening to management closely during the live conference call following the earnings release. It's often during this call that the company reveals the most useful tidbits about its vision.

Here are three questions, along with some helpful background information related to each topic, the CEO will hopefully address.

Apple CEO Tim Cook. Image source: Apple.

How long can iPhone sales grow?
This is the big question headed into Apple's fourth-quarter results. After a year of monstrous year-over-year growth in iPhone sales, investors will look to the company's guidance for the holiday quarter to see whether management thinks it can continue to grow smartphone sales from its record year. Will the iPhone 6s and 6s Plus, which were launched in September, be enough to help Apple outperform the blockbuster success of its iPhone 6 and 6 Plus?

Apple's guidance for its holiday quarter, which is its first fiscal quarter of 2016, will mark the company's first full quarter of availability of the iPhone 6s and 6s Plus, making guidance for the quarter particularly insightful into management's confidence in the product.

Cook is no stranger to this narrative. When asked about whether there is still room for iPhone sales growth during the third-quarter conference call, he said he believes there is still more upside left, citing the fact that only 27% of Apple's iPhone installed base had upgraded to the iPhone 6 or 6 Plus. He also noted that the tech giant is seeing the highest rate of users switching from Android devices to iOS devices it has ever observed.

Is Cook still this bullish on smartphones as the company begins to face up against its tough year-over-year comparisons from the iPhone 6 and 6 Plus first-year sales?

Where does TV go from here?
Cook believes the new, overhauled Apple TV represents the beginning of a fundamental shift in the way consumers experience television, according to his recent comments in a Wall Street Journal interview. Non-linear platforms that let users interact with television, similar to the way they interact with smartphones, are the "foundation of the future of TV," he explained.

But how significant of a role in this transformation of the TV experience does Cook believe Apple will play?

Apple TV. Image source: Apple.

Look for more insight into how seriously Apple is going to pursue television and content during the earnings call.

Will iPad overtake Mac?
With the new 12.9-inch iPad Pro set to launch next month, it's clear the company believes there is a middle ground between laptops and PCs. But it wasn't always this way. Three years ago, Cook referred to Microsoft's Surface as a "compromised and confusing product."

"I suppose you could design a car that flies and floats, but it wouldn't do all of those things very well," Cook said in reference to Microsoft's Surface during a 2012 fourth-quarter earnings call. 

Sure, Cook didn't entirely cave yet on the concept of designing a product as in between a laptop and a tablet as the Surface is. The iPad Pro is still far more tablet than it is a laptop, not quite qualifying as hybrid or "convertible." But given the higher price point, the use of "Pro" in the name, and the introduction of the Apple Stylus, there is a clear shift closer toward the productivity levels implied by a laptop.

iPad Pro. Image source: Apple.

The company's attempt to build a tablet for professionals prompts an important question: Is Apple leaning toward a future in which iPad sales will eventually exceed Mac sales by a wide margin?

Apple will release its fourth-quarter results after market close on Tuesday, Oct. 27. Tune in to the live conference call at 2:00 p.m. Pacific time. 

For a preview of Apple's fourth-quarter results, check out this earnings preview.