Q: What mistakes do candidates make on this AQA GCSE question?

✗ Using an `if` statement instead of a `while` loop, which would only allow for one payment.\n✗ Forgetting to handle the case where a tip is paid (i.e., the final balance is negative).\n✗ Incorrectly calculating the tip (e.g., printing the negative number).

Question 1

A group of people have a meal in a restaurant. Instead of one person paying for the whole meal, each person will pay for what they eat.

Write a Python program that asks each person in the group how much they are paying towards the meal and works out when the bill is fully paid. Each person can pay a different amount.

The program should:
- get the user to enter the total amount of the bill
- get a person to enter how much they are paying towards the bill
- subtract the amount entered from the bill:
  - if the amount left to pay is more than 0, output how much is left to pay and repeat until the amount left to pay is 0 or less
  - if the amount left to pay is 0, then output the message `Bill paid`
  - if the amount left to pay is less than 0, then output the message `Tip is` and the difference between the amount left to pay and 0

You **should** use indentation as appropriate, meaningful variable name(s) and Python syntax in your answer.

Accepted Answer

1.  **Get Total Bill:** Start by asking the user for the total bill. Use `float()` to allow for pounds and pence. Store this in `total_bill`.
2.  **Create a Loop:** A `while` loop is perfect here. The condition should be `while total_bill > 0:`. This means the loop will continue as long as there is money outstanding.
3.  **Get Payment:** Inside the loop, ask for the next person's payment amount, again using `float()`. Store it in a variable like `payment`.
4.  **Update Total:** Subtract the payment from the total bill: `total_bill = total_bill - payment` or `total_bill -= payment`.
5.  **Provide Feedback:** Inside the loop, add an `if` statement: `if total_bill > 0:`. If true, print the remaining amount so the next person knows what is left to pay.
6.  **Handle Final Output:** After the `while` loop finishes (which only happens when `total_bill` is 0 or less), you need to determine the final message.
7.  Use an `if/else` statement. `if total_bill == 0:`, print "Bill paid".
8.  The `else` block will catch the case where `total_bill < 0`. In this case, calculate the tip by making the negative `total_bill` positive (e.g., `tip = -total_bill`). Then print the tip amount.

Question 2

What mistakes do candidates make on this AQA GCSE question?

Accepted Answer

✗ Using an `if` statement instead of a `while` loop, which would only allow for one payment.
✗ Forgetting to handle the case where a tip is paid (i.e., the final balance is negative).
✗ Incorrectly calculating the tip (e.g., printing the negative number).

How to approach this question

Full Answer

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