Brief Overview of Python — NCERT Solutions

Invalid identifier names are:

• a) Serial_no. — contains a dot (.), which is not allowed.
• b) 1st_Room — starts with a digit, and an identifier cannot start with a digit.
• c) Hundred$`** — contains **`$, a special symbol not allowed.
• d) Total Marks — contains a space, which is not allowed.
• f) total-Marks — contains a hyphen (-), which is not allowed.
• h) True — it is a keyword/reserved word, so it cannot be used as an identifier.

Valid identifiers are e) Total_Marks and g) _Percentage.

The required assignment statements are:

length = 10
breadth = 20

sum = (length + breadth) / 2

stationery = ['Paper', 'Gel Pen', 'Eraser']

first = 'Mohandas'
middle = 'Karamchand'
last = 'Gandhi'

fullname = first + ' ' + middle + ' ' + last

The blank spaces are added using ' ' so the full name is joined properly.

The suitable data types are:

• a) Number of months in a year — int, because it is a whole number.
• b) Resident of Delhi or not — bool, because it has only two values: yes/no, true/false.
• c) Mobile number — str, because it is better treated as a string of digits and may contain leading zeroes.
• d) Pocket money — float, because it may include paise/decimal part.
• e) Volume of a sphere — float, because it may come as a decimal value.
• f) Perimeter of a square — float, because the side length may be fractional, so the result may also be decimal.
• g) Name of the student — str, because it is text.
• h) Address of the student — str, because it is text.

Step by step:

• a) num1 += num2 + num3 means num1 = num1 + (num2 + num3)
• num2 + num3 = 3 + 2 = 5
• num1 = 4 + 5 = 9

• b) print(num1) prints 9.

• c) num1 = num1 ** (num2 + num3)
• num2 + num3 = 3 + 2 = 5
• num1 = 9 ** 5 = 59049 if using the updated value from part (a)

But in such textbook output questions, each part is usually treated separately unless stated otherwise. Since the question says “when num1 = 4, num2 = 3, num3 = 2”, the sequence is interpreted in order. Therefore after (a), num1 is 9, so:

• num1 = 9 ** 5 = 59049

• d) print(num1) prints 59049.

• e) num1 = num2 + c causes an error because c is not defined**.

• f) num1 = '5' + '5' joins strings, so the result is '55'.

• g) print(num1) prints 55.

• h) print(4.00/(2.0+2.0))
• denominator 2.0 + 2.0 = 4.0
• 4.00 / 4.0 = 1.0

• i) num1 = 2 + 9*((3*12)-8)/10
• 3*12 = 36
• 36 - 8 = 28
• 9 * 28 = 252
• 252 / 10 = 25.2
• 2 + 25.2 = 27.2

So num1 becomes 27.2.

• j) print(num1) prints 27.2.

• k) num1 = float(10) converts to 10.0.

• l) print(num1) prints 10.0.

• m) num1 = int('3.14') gives an error because '3.14' is not a valid integer string.

• n) print(num1) is not executed because the program has already stopped at the error in (m).

• o) print(10 != 9 and 20 >= 20)
• 10 != 9 is True
• 20 >= 20 is True
• True and True is True

• p) print(5 % 10 + 10 < 50 and 29 <= 29)
• 5 % 10 = 5
• 5 + 10 = 15
• 15 < 50 is True
• 29 <= 29 is True
• True and True is True

So the outputs/values are as listed above.

• a) 25 / 0 — runtime error, because division by zero cannot be executed.
• b) num1 = 25; num2 = 0; num1 / num2 — runtime error, because the division by zero occurs during execution.

# Calculate amount payable on simple interest
P = float(input("Enter principal: "))
R = float(input("Enter rate of interest: "))
T = float(input("Enter time in years: "))

SI = (P * R * T) / 100
Amount = P + SI

print("Simple Interest =", SI)
print("Amount payable =", Amount)