1. A trivial example: flipping a coin¶

Question:

A coin is tossed for 100 times, heads appeared 65 times, tails appeared 35 times. Construct a hypothesis test to check whether the coin is fair. ($P_{head}=P_{tail}=\frac{1}{2}$)

Hypothesis: $$H_0:P_{h}=0.5, H_a:P_{h}\neq 0.5$$

(1) Z test¶

Since for binomial distribution, each trial is either 0 or 1, so the sample mean is also the proportion of success. Since for this experiment, we already know the distribution of tossing a coin is a binomial distribution, let $X$ to be the count of successes, then: $$\mu_X = np$$ $$\sigma^2_X=np(1-p)$$ $$X \sim N(np, np(1-p))$$

Getting Started¶

In this project, you will analyze a dataset containing data on various customers' annual spending amounts (reported in monetary units) of diverse product categories for internal structure. One goal of this project is to best describe the variation in the different types of customers that a wholesale distributor interacts with. Doing so would equip the distributor with insight into how to best structure their delivery service to meet the needs of each customer.

I resolved all the database questions on Leetcode.com recently. The questions cover most of the SQL common queries inlcuding JOIN, Ranking and other SQL basics. I provided the answers as well as explanations in this blog, as a way to consolidate the SQL knowledge.

The questions on Leetcode only support MySQL, so you can install MySQL on your laptop for testing purpose before submitting the solution, or use online SQL platforms to test you query. E.g. rextester more ...

Table of Contents¶