source.list correct ?

Deal all,

I aquiered a Jetson nano few weeks ago and I am in trouble to follow any tutorial because any time I have to install a new package I end up with the following error message. I am starting to think that I have an issue with my source.list file.
How can I be sure of the following things :
1-my source.list file is correctly configured
2-the package I want is available on the source I have configured

Package python3-numpy is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Unable to locate package libpython3-dev
E: Package 'python3-numpy' has no installation candidat

Below example of issues I had but I found out on https://packages.ubuntu.com/bionic that they existe for my linux distribution :

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package hdf5-tools

But I found it : https://packages.ubuntu.com/bionic/hdf5-tools

Below my source file

See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to

newer versions of the distribution.

deb http://us.archive.ubuntu.com/ubuntu/ bionic main restricted

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic main restricted

Major bug fix updates produced after the final release of the

distribution.

deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-updates main restricted

N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu

team. Also, please note that software in universe WILL NOT receive any

review or updates from the Ubuntu security team.

deb http://us.archive.ubuntu.com/ubuntu/ bionic universe

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic universe

deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates universe

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-updates universe

N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu

team, and may not be under a free licence. Please satisfy yourself as to

your rights to use the software. Also, please note that software in

multiverse WILL NOT receive any review or updates from the Ubuntu

security team.

deb http://us.archive.ubuntu.com/ubuntu/ bionic multiverse

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic multiverse

deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-updates multiverse

N.B. software from this repository may not have been tested as

extensively as that contained in the main release, although it includes

newer versions of some applications which may provide useful features.

Also, please note that software in backports WILL NOT receive any review

or updates from the Ubuntu security team.

deb http://us.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-backports main restricted universe multiverse

Uncomment the following two lines to add software from Canonical’s

‘partner’ repository.

This software is not part of Ubuntu, but is offered by Canonical and the

respective vendors as a service to Ubuntu users.

deb http://archive.canonical.com/ubuntu bionic partner

deb-src http://archive.canonical.com/ubuntu bionic partner

deb http://ports.ubuntu.com/ubuntu-ports/ bionic-security main restricted universe

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-security main restricted

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-security universe

deb http://ports.ubuntu.com/ubuntu-ports/ bionic-security multiverse

deb-src http://ports.ubuntu.com/ubuntu-ports/ bionic-security multiverse

deb http://ports.ubuntu.com/ubuntu-ports/ bionic main universe multiverse restricted

Thank you in advance for your tips