Structured Programming — practice questions

The problem is 'Find highest and lowest scores for 25 students'.

Level 0: Process class scores.

Stepwise Refinement (Level 1):

1. Initialise variables (e.g., HighestScore, LowestScore).
2. Input and process scores for all 25 students.
3. Output the final HighestScore and LowestScore.

Further Refinement (Level 2) of Step 1 & 2: 1.1. Input the first score. 1.2. Set HighestScore and LowestScore to this first score. 2.1. Loop 24 times (for the remaining students). 2.2. Inside the loop: Input the next score. 2.3. If the new score is greater than HighestScore, update HighestScore. 2.4. If the new score is less than LowestScore, update LowestScore.

Final Pseudocode:

DECLARE HighestScore, LowestScore, StudentScore : INTEGER

INPUT StudentScore
HighestScore <- StudentScore
LowestScore <- StudentScore

FOR Counter <- 1 TO 24
  INPUT StudentScore
  IF StudentScore > HighestScore THEN
    HighestScore <- StudentScore
  ENDIF
  IF StudentScore < LowestScore THEN
    LowestScore <- StudentScore
  ENDIF
NEXT Counter

PRINT "Highest score is: ", HighestScore
PRINT "Lowest score is: ", LowestScore

This problem can be broken down into: get input, calculate base cost, determine if a discount applies, calculate final cost, and output the result.

Pseudocode Solution:

DECLARE NumItems : INTEGER
DECLARE ItemCost, TotalCost : REAL
CONSTANT DiscountRate = 0.10
CONSTANT ItemPrice = 2.50

// Sequence: Get input first
INPUT NumItems

// Sequence: Calculate initial cost
TotalCost <- NumItems * ItemPrice

// Selection: Check for discount condition
IF NumItems >= 10 THEN
  // Sequence: Calculate and apply discount
  TotalCost <- TotalCost - (TotalCost * DiscountRate)
ENDIF

// Sequence: Output the final result
PRINT "The final cost is: £", TotalCost

Marking Points:

1. Correct declaration of variables.
2. Correct input of NumItems.
3. Correct initial calculation of TotalCost.
4. Correct IF statement (selection) with the right condition ($>= 10$).
5. Correct calculation of the discounted cost inside the IF block.
6. Correct output of the final TotalCost.