Problem solving and programming

Explain the purpose of each type of test: normal, boundary, erroneous and integration.

Explain the difference between a function and a procedure.

Write a Python function that takes a list of integers and returns the second-largest distinct value, or None if there is none.

The code below should print the average of the scores but contains errors.

def average(values):    total = 0    for i in range(1, len(values)):        total = total + values[i]    return total / len(values) scores = [12, 15, 9, 20]print("Average is " + average(scores))

Identify and correct three errors.

Using the data below, write a function clean(readings) that returns a new list without the -999 values, and a function stats(values) that returns the minimum, maximum and mean (rounded to 1 d.p.).

readings = [18.5, 19.2, 21.0, -999, 22.4, 23.1, 20.7, -999, 19.8, 18.9]# -999 means the sensor failed to record a value

Write a program that repeatedly asks a user to enter temperature readings (or 'done' to finish), validates each one (must be a number between −50 and 60), stores valid readings, and then outputs: the number of readings, the mean, and how many readings were above the mean. Use at least two functions.

Extend your program so that the valid readings are saved to a text file, one per line, and can be loaded again when the program next starts.

Write a recursive function that returns the sum of the digits of a positive integer (e.g. 4071 → 12) and explain how the base case prevents infinite recursion.

Evaluate the efficiency of your solutions to Questions 3 and 5. Suggest how they could be improved for a data set of 10 million readings.