Answer: C
Time shifting is when you move from one period in time to another.
Answer:
- import math
-
- def standard_deviation(aList):
- sum = 0
- for x in aList:
- sum += x
-
- mean = sum / float(len(aList))
-
- sumDe = 0
-
- for x in aList:
- sumDe += (x - mean) * (x - mean)
-
- variance = sumDe / float(len(aList))
- SD = math.sqrt(variance)
-
- return SD
-
- print(standard_deviation([3,6, 7, 9, 12, 17]))
Explanation:
The solution code is written in Python 3.
Firstly, we need to import math module (Line 1).
Next, create a function standard_deviation that takes one input parameter, which is a list (Line 3). In the function, calculate the mean for the value in the input list (Line 4-8). Next, use the mean to calculate the variance (Line 10-15). Next, use sqrt method from math module to get the square root of variance and this will result in standard deviation (Line 16). At last, return the standard deviation (Line 18).
We can test the function using a sample list (Line 20) and we shall get 4.509249752822894
If we pass an empty list, a ZeroDivisionError exception will be raised.
Answer:
Refer below.
Explanation:
VPC, Subnets, Route Table(s), Nat Gateway, and Internet Gateway. These are the least required services to provide internet access to a private EC2 instance. NAT gateway requires an internet gateway.
Answer:
Importance of backup in system administration:
Backups are crucial in system administrations for preserving continuity and protecting against specific types of hardware failures, service interruptions, and human mistakes. To aid a company in recovering from an unexpected catastrophe, backup copies make it possible to restore data to a previous point in time. To safeguard against primary data loss or corruption, it is essential to save a copies of data on a different media. When a system administrator create a backup, he makes a copy of the data that you can restore if your main data is lost. These errors may be the consequence of faulty hardware or software, corrupted data, or a human error like a targeted attack or an unintentional deletion. System backup and recovery is therefore a crucial skill for system administrators as well as the companies they work for.
Three methods for performing backup:
- Disk image: A efficient method to back up not only the files and directories but also everything else on the system is by creating a disk image. If a user have a disk image, the user can restore everything, including the operating system, applications, data, and more, so the user won't have to worry about any difficulties. Placing the disk image-containing DVD into the DVD-ROM to restore the backup. Additionally, just attach an external HDD to the computer if the user have a disk image that they made.
- External hard drive: The most common backup method is to use an external hard drive or even a USB flash drive. An HDD can be easily, quickly, and affordably backed up. It is effective since consumers may carry their portable backup with them wherever they go.
- Cloud backup: Cloud backup or Online backup has been around for a while, but not many people really utilize it. But the greatest backup technique by far is cloud backup. The user does not have to worry about hardware problems because their files are saved in the cloud and can be accessed from anywhere because the backups are automatically produced and everything is synchronized. It is one of the greatest methods to backup, especially when you consider that the contents are encrypted and stored securely.
