Time Series Forecast based on market share (market penetration)

Hi everyone,

I have the following exercise:

A number of car companies in a communist society are producing only one model of a car each. They obviously know their sales, but they don't know if their car is used as sport car, as an adventurous car or as a city car. However, they can get, from a third party company, the market penetration of their car use as Sport car, 4x4 car or City car.

In other words, they know that in 2010 Q1 company 1 sold 765,000 units and know that the market penetration of that car was: 45% used as sport car, 34% used as 4x4 car, and 37% used as a city car.

Now, would it be possible to build a model or a time series forecast that predicts sales based on the market penetration for each car?

Thanks in advance for your help!

attached file
time series forecast.xlsx

What do you mean? You can't see the file?

I still need a bit of help. Thanks in advance!

That's exactly what I wanted.

Thanks a lot!!!