Hackerrank in R: Basic Statistics Warmup Challenge

Hackerrank is my latest amazing and scary discovery. It’s amazing because I get to solve a problem with ready test cases and I can submit my solutions unlimited time and moreover I get some points on submission. Well, it’s scary as I really struggled at the warmup exercise when I was expecting to finish in a couple of mins! 

The problem is here: 
This exercise is to calculate the Mean, Median, Mode, Standard Deviation, and Confidence Interval for the Mean. Below is the basic summary:

Mean (m): The average of all the integers.

Median: In case, the number of integers is odd, the middle element; else, the average of the middle two elements.

Mode: The element(s) which occurs most frequently. If multiple elements satisfy this criterion, Mode is the numerically smallest one.

Standard Deviation (SD): Square root of the average squared distance from the mean.
sd = √(Σ(x_i – μ)² /n)
where x_{i  =} each element in the sample
            μ = the mean
            n = Sample Size

Confidence Interval for the mean: A 95% confidence interval is a range of values that we can be 95% certain contains the true mean of the population.  

CI =  μ ± z * σ/√n
where μ= the Mean
            z = z* value from the standard normal distribution
            σ = the Standard Deviation
            n = Sample Size

Example: z* values for various Confidence Levels

Confidence Level        z* value
——————————————————
80 %                                 1.28
90%                                  1.645
95%                                   1.96

Okay, now the code part: