1.26. Dictionaries 5

Dictionaries in Python are useful types to create lookup tables and small databases. In this question you will design such a mini-database to hold the grades of 3 students.

In this database you will hold 2 grades (midterm and final grades) of a student as a tuple. These tuples must be indexed with the id of the student.

After the information needed to create this database is given, you will be given an id for one of the students to calculate the average of his/her grades.

So, input format will be given in each line in the following order:

  • ID of the 1st Student

  • Midterm Grade of the 1st Student

  • Final Grade of the 1st Student

  • ID of the 2nd Student

  • Midterm Grade of the 2nd Student

  • Final Grade of the 2nd Student

  • ID of the 3rd Student

  • Midterm Grade of the 3rd Student

  • Final Grade of the 3rd Student

  • ID of the student whose grades will be calculated

IDs will be given as integers and grades will be given as floats. You should output the calculated average grade of the given student as a float. 1 digit after the decimal point is sufficient for this output.

Hint: While creating the database, you can use the same variables instead of defining new ones.

Sample I/O:

Input:
1234567
40
70
3334444
90
80
2981356
35.4
12
2981356

Output:
23.7

db = dict()

student_id = int(input())
midterm = float(input())
final = float(input())
db[student_id] = (midterm, final)

student_id = int(input())
midterm = float(input())
final = float(input())
db[student_id] = (midterm, final)

student_id = int(input())
midterm = float(input())
final = float(input())
db[student_id] = (midterm, final)

student_id = int(input())

(midterm, final) = db[student_id]   # notice the tuple matching
average = (midterm + final) / 2
print("{:.f}".format(average))