Creation and Setting of background images in android application

[Kamal14042015]

Hello,

I am new to android application development and i am currently working on an existing android application. I have couple of questions regarding the creation & setting of background images in the application

1) In the existing project I found that the images are set based on different dpi levels. But I found that there are different devices with different screen resolutions for same dpi value. For e.g., in latest Android Studio (v.3.5) in the AVD manager I found following screen resolutions for the same dpi “~420 dpi”.

a. Which resolution should I chose to set the background image?
b. Do I need to set image for highest screen resolution among them and
it will be automatically scaled to other resolutions under same dpi?
c. If it is needed to set different images for different resolutions
under same dpi, how to differentiate them?
7.3” Foldable – 1536x2152
8” Foldable – 2200x2480
Nexus 5X – 1080x1920​

2) As per this Android link , I have only found the following list for different dpi values. Under which category does 420 dpi fall?

ldpi – 120dpi
mdpi – 160dpi
hdpi – 240dpi
xhdpi – 320dpi
xxhdpi – 480dpi
xxxhdpi – 640dpi​

Thanks and Regards,
Kamal