2. Question 2
A payment system needs a query that calculates the total commission for all transactions made by a customer.
A commission is a fee that is calculated based on the customer's country of origin.
Expected Output Columns
| Column | Description |
|---|---|
| Customer email address | |
| country | Customer country |
| transactions | Total number of all transactions for a customer |
| total_amount | Total amount of all transactions for a customer |
| total_commission | Total commission for all transactions for a customer, rounded to two decimal places |
The result should be sorted in ascending order by email.
Note
- The total commission is the sum of the products of the transaction amounts and the commission of the client's country.
Schema
customers
| name | type | constraint |
|---|---|---|
| id | INT | PRIMARY KEY |
| VARCHAR(255) | ||
| country | VARCHAR(255) | FOREIGN KEY (country → countries.name) |
countries
| name | type | constraint | description |
|---|---|---|---|
| name | VARCHAR(255) | PRIMARY KEY | Country name |
| commission | DECIMAL(3,2) | Country commission |
transactions
| name | type | constraint |
|---|---|---|
| customer_id | INT | FOREIGN KEY (customer_id → customers.id) |
| amount | DECIMAL(5,2) |
3. Question 3
In how many ways can the letters of the word 'HACKER' be rearranged such that the vowels always appear together?
Options:
- 5! × 2!
- 6!
- 6! × 2!
- 5!
4. Question 4
In a family, there are two parents: Alex and Jordan. The probability that at least one parent falls ill is 20%, and the probability that both parents fall ill is 5%. The probability that neither parent falls ill is 80%. If the probability that Alex falls ill is 12%, what is the probability that Jordan falls ill?
Options:
- 3%
- 13%
- 15%
- 8%
5. Question 5
Statement 1: A has two children. The older child is a girl. The probability that both children are girls is p1.
Statement 2: B has two children. At least one of them is a boy. The probability that both children are boys is p2.
Based on this, what is the correct relationship between p1 and p2?
Options:
- p1 = p2
- p1 > p2
- p2 > p1
- It cannot be determined.
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