Ntpd: command not found during installing on ubuntu using the package

I purged mycroft-core and I am trying to re-install it and see the following error

sudo apt-get install mycroft-core

Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 0 to remove and 1 not upgraded.
Need to get 0 B/23.9 MB of archives.
After this operation, 0 B of additional disk space will be used.
Selecting previously unselected package mycroft-core.
(Reading database ... 264874 files and directories currently installed.)
Preparing to unpack .../mycroft-core_0.8.18_amd64.deb ...
The user `mycroft' is already a member of `input'.
The user `mycroft' is already a member of `audio'.
The user `mycroft' is already a member of `dialout'.
Unpacking mycroft-core (0.8.18) ...
Processing triggers for systemd (229-4ubuntu17) ...
Processing triggers for ureadahead (0.100.0-19) ...
Setting up mycroft-core (0.8.18) ...
Initializing init script for mycroft-messagebus
Initializing init script for mycroft-skills
Initializing init script for mycroft-speech-client
/var/lib/dpkg/info/mycroft-core.postinst: line 64: ntpd: command not found
Starting Mycroft service mycroft-messagebus
Starting Mycroft service mycroft-skills
Starting Mycroft service mycroft-speech-client
This system architecture has been detected as: x86_64
Checking to see if we need to apply the Picroft alsa audio fix in configuration
changed ownership of '/home/mycroft/.mycroft/mycroft.conf' from root:root to mycroft:mycroft

About the laptop:

lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.2 LTS
Release:        16.04
Codename:       xenial

uname -a

Linux oren 4.4.0-83-generic #106-Ubuntu SMP Mon Jun 26 17:54:43 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux