You have a data file that contains two trillion records, one record per line (comma separated).
Each record lists two friends and unique message sent between them. Their names will not have
commas.
Michael, John, Pabst, Blue Ribbon
Tiffany, James, BMX Racing
John, Michael, Natural Lemon Flavor
Analyze the pseudo code examples below and determine which set of mappers and reducers in
the below pseudo code snippets will solve for the mean number of messages each user sends to
all of the friends?
For example pseudo code may have three friends to whom he sends 6, 10, and 200 messages,
respectively, so Michael’s mean would be (6+10+200)/3. The solution may require a pipeline of
two MapReduce jobs.

You have just run a MapReduce job to filter user messages to only those of a selected
geographical region. The output for this job in a directory named westUsers, located just below
your home directory in HDFS. Which command gathers these records into a single file on your
local file system?

Function is convex if the line segment between two points, a and b is greater than equal to the
value of the a x b

Which two functions are convex?

You need to analyze 60,000,000 images stored in JPEG format, each of which is approximately 25
KB. Because your Hadoop cluster isn’t optimized for storing and processing many small files you
decide to do the following actions:
1. Group the individual images into a set of larger files
2. Use the set of larger files as input for a MapReduce job that processes them directly with
Python using Hadoop streaming
Which data serialization system gives you the flexibility to do this?

You have user profile records in an OLTP database that you want to join with web server logs
which you have already ingested into HDFS. What is the best way to acquire the user profile for
use in HDFS?

You are building a system to perform outlier detection for a large online retailer. You need to build
a system to detect if the total dollar value of sales are outside the norm for each U.S. state, as
determined from the physical location of the buyer for each purchase.
The retailer’s data sources are scattered across multiple systems and databases and are
unorganized with little coordination or shared data or keys between the various data sources.
Below are the sources of data available to you. Determine which three will give you the smallest
set of data sources but still allow you to implement the outlier detector by state.

How can the naiveté of the naive Bayes classifier be advantageous?

What are two defining features of RMSE (root-mean square error or root-mean-square deviation)?

Consider the following sample from a distribution that contains a continuous X and label Y that is
either A or B:

Which is the best cut point for X if you want to discretize these values into two buckets in a way
that minimizes the sum of chi-square values?

Consider the following sample from a distribution that contains a continuous X and label Y that is
either A or B:

Which is the best choice of cut points for X if you want to discretize these values into three buckets
that minimizes the sum of chi-square values?