Chapter 5 Getting Started with Python | class 11th | Ncert solution for computer

NCERT Solutions Class 11 Computer Science Chapter 5 Getting Started with Python

Question 1. Which of the following identifier names are invalid and why?

i Serial_no.                     v Total_Marks

ii 1st_Room                   vi total-Marks

iii Hundred$                   vii _Percentage

iv Total Marks                viii True

Answer:

i) Serial_no. :- Invalid

Reason- (.) is not allowed in identifier

ii) 1st_Room :- Invalid

Reason- identifier can’t start with number

iii) Hundred$ :-  Invalid

Reason- We can’t use special symbol $ in identifier

iv) Total Marks :- Invalid

Reason- We can’t use space between in identifier

v) Total_Marks :- Valid

Reason- We can use underscore between in identifier

vi) total-Marks :- Invalid

Reason- We can’t use hyphen between in identifier

vii) _Percentage:- Invalid

Reason- Identifier can’t begin with underscore

viii) True :- Invalid

Reason- We can’t use keyword as a identifier

Question 2. Write the corresponding Python assignment statements:

a) Assign 10 to variable length and 20 to variable breadth.

b) Assign the average of values of variables length and breadth to a variable sum.

c) Assign a list containing strings ‘Paper’, ‘Gel Pen’, and ‘Eraser’ to a variable stationery.

d) Assign the strings ‘Mohandas’, ‘Karamchand’, and ‘Gandhi’ to variables first, middle and last.

e) Assign the concatenated value of string variables first, middle and last to variable fullname. Make sure to incorporate blank spaces appropriately between different parts of names.

Answer:

a) Assign 10 to variable length and 20 to variable breadth.

length = 10

breadth = 20

b) Assign the average of values of variables length and breadth to a variable sum.

Sum = (length + breadth)/2

c) Assign a list containing strings ‘Paper’, ‘Gel Pen’, and ‘Eraser’ to a variable stationery.

Stationary=[‘Paper’ ,  ‘Gel Pen’ , ‘Eraser’

d) Assign the strings ‘Mohandas’, ‘Karamchand’, and ‘Gandhi’ to variables first, middle and last.

first = ‘Mohandas’

middle= ‘Karamchand’

last= ‘Gandhi’

e) Assign the concatenated value of string variables first, middle and last to variable fullname. Make sure to incorporate blank spaces appropriately between different parts of names.

fullname = first +” “+ middle +” “+ last

Question 3. Write logical expressions corresponding to the following statements in Python and evaluate the expressions (assuming variables num1, num2, num3, first, middle, last are already having meaningful values):

a) The sum of 20 and –10 is less than 12.

b) num3 is not more than 24.

c) 6.75 is between the values of integers num1 and num2.

d) The string ‘middle’ is larger than the string ‘first’ and smaller than the string ‘last’.

e) List Stationery is empty.

Answer:

STATEMENT	LOGICAL EXPRESSIONS
The sum of 20 and –10 is less than 12.	(20 + (-10)) < 12
num3 is not more than 24.	num3 <= 24   or not(num3 > 24)
6.75 is between the values of integers num1 and num2.	(6.75 >= num1) and (6.75 <= num2)
The string ‘middle’ is larger than the string ‘first’ and smaller than the string ‘last’.	(middle > first) and (middle < last)
List Stationery is empty.	len(Stationery) == 0

Question 4. Add a pair of parentheses to each expression so that it evaluates to True.

a) 0 == 1 == 2

b) 2 + 3 == 4 + 5 == 7

c) 1 < -1 == 3 > 4

Answer:

EXPRESSION	EXPRESSION WITH PARENTHESIS
0 == 1 == 2	(0 == (1 == 2))
2 + 3 == 4 + 5 == 7	(2 + (3 == 4 )+ 5) == 7
1 < -1 == 3 > 4	(1 < -1 ) == (3 > 4)

Question 5. Write the output of the following:

a) num1 = 4

num2 = num1 + 1

num1 = 2

print (num1, num2)

b) num1, num2 = 2, 6

num1, num2 = num2, num1 + 2

print (num1, num2)

c) num1, num2 = 2, 3

num3, num2 = num1, num3 + 1

print (num1, num2, num3)

Answer:

a) num1 = 4

num2 = num1 + 1

num1 = 2

Output: 2,5

b) num1, num2 = 2, 6

num1, num2 = num2, num1 + 2

print (num1, num2)

Output: 6,4

c) num1, num2 = 2, 3

num3, num2 = num1, num3 + 1

print (num1, num2, num3)

Output: error

Question 6. Which data type will be used to represent the following data values and why?

a) Number of months in a year

b) Resident of Delhi or not

c) Mobile number

d) Pocket money

e) Volume of a sphere

f) Perimeter of a square

g) Name of the student

h) Address of the student

Answer:

DATA VALUES	DATA TYPES	REASON
Number of months in a year	Integer	Number of months contain only number values (integer).
Resident of Delhi or not	Boolean	It gives the answer in the form of true and false
Mobile number	Integer	Mobile number only contain integer number value
Pocket money	Float	Money can be count as 100rs 50 paisa(100.50)
Volume of a sphere	Float	The volume can be calculated in the decimal point
Perimeter of a square	Float	The perimeter can be calculated in the decimal point
Name of the student	String	Name is a set of character, hence data type of name of student is string
Address of the student	String	Address is a set of character, hence data type of address of student is string

Question 7. Give the output of the following when num1 = 4, num2 = 3, num3 = 2

a) num1 += num2 + num3

print (num1)

b) num1 = num1 ** (num2 + num3)

print (num1)

c) num1 **= num2 + num3

d) num1 = ‘5’ + ‘5’

print(num1)

e) print(4.00/(2.0+2.0))

f) num1 = 2+9*((3*12)-8)/10

print(num1)

g) num1 = 24 // 4 // 2

print(num1)

h) num1 = float(10)

print (num1)

i) num1 = int(‘3.14’)

print (num1)

j) print(‘Bye’ == ‘BYE’)

k) print(10 != 9 and 20 >= 20)

l) print(10 + 6 * 2 ** 2 != 9//4 -3 and 29

>= 29/9)

m) print(5 % 10 + 10 < 50 and 29 <= 29)

n) print((0 < 6) or (not(10 == 6) and

(10<0)))

Answer:

a) num1 += num2 + num3

print (num1)

Output:9

b) num1 = num1 ** (num2 + num3)

print (num1)

Output:1024

c) num1 **= num2 + num3

Output:1024

d) num1 = ‘5’ + ‘5’

print(num1)

Output:55

e) print(4.00/(2.0+2.0))

Output:1.0

f) num1 = 2+9*((3*12)-8)/10

print (num1)

Output:27.2

g) num1 = 24 // 4 // 2

print(num1)

Output:3

h) num1 = float(10)

print (num1)

Output:10.0

i) num1 = int(‘3.14’)

print (num1)

Output: error

j) print(‘Bye’ == ‘BYE’)

Output: False

k) print(10 != 9 and 20 >= 20)

Output:True

l) print(10 + 6 * 2 ** 2 != 9//4 -3 and 29

>= 29/9)

Output: True

m) print(5 % 10 + 10 < 50 and 29 <= 29)

Output: True

n) print((0 < 6) or (not(10 == 6) and

(10<0)))

Output: True

Question 8. Categorise the following as syntax error, logical error or runtime error:

a) 25 / 0

b) num1 = 25; num2 = 0; num1/num2

Answer:

a) 25 / 0 :- Runtime Error, because of divisible by zero

b) num1 = 25; num2 = 0; num1/num2 :- Runtime Error, because of divisible by zero

Question 9. A dartboard of radius 10 units and the wall it is hanging on are represented using a two-dimensional coordinate system, with the board’s center at coordinate (0,0). Variables x and y store the x-coordinate and the y-coordinate of a dart that hits the dartboard. Write a Python expression using variables x and y that evaluates to True if the dart hits (is within) the dartboard, and then evaluate the expression for these dart coordinates:

a) (0,0)

b) (10,10)

c) (6, 6)

d) (7,8)

Question 10. Write a Python program to convert temperature in degree Celsius to degree Fahrenheit. If water boils at 100 degree C and freezes as 0 degree C, use the program to find out what is the boiling point and freezing point of water on the Fahrenheit scale. (Hint: T(°F) = T(°C) × 9/5 + 32)

Answer:

deffar_conv(t):

x=t*9/5 + 32

return x

print(far_conv(100))

Question 11. Write a Python program to calculate the amount payable if money has been lent on simple interest. Notes Ch 5.indd 117 08-Apr-19 12:35:13 PM 2020-21 118 Computer Science – Class xi Principal or money lent = P, Rate of interest = R% per annum and Time = T years. Then Simple Interest (SI) = (P x R x T)/ 100. Amount payable = Principal + SI. P, R and T are given as input to the program.

Answer:

principal=int(input(“P=”))

rate=int(input(“I=”))

time=int(input(“T=”))

defamount_pay(principal,rate,time):

simple_intrest=(principal*rate*time)/100

TOTAL_amount=Print+simple_intrest

returnTOTAL_amount

print(“Total Payble amount”)

print(amount_pay(principal,rate,time))

Question 12.Write a program to calculate in how many days a work will be completed by three persons A, B and C together. A, B, C take x days, y days and z days respectively to do the job alone. The formula to calculate the number of days if they work together is xyz/(xy + yz + xz) days where x, y, and z are given as input to the program.

Answer:

x=int(input(“x=”))

y=int(input(“Y=”))

z=int(input(“Y=”))

defwork_days(x,y,z):

days=x*y*z/(x*y+y*z+z*x)

return days

print(“Work will complet(in days)”)

print(work_days(x,y,z))

Question 13. Write a program to enter two integers and perform all arithmetic operations on them.

Answer:

a=int(input(“Enter First Number: “))

b=int(input(“Enter Second Number: “))

defAddtion(a,b):

returna+b

def subtraction(a,b):

return a-b

def multiplication(a,b):

return a*b

def division(a,b):

return a/b

print(“Addtion of {0} & {1} is : “.format(a,b))

print(Addtion(a,b))

print(“subtraction of {0} & {1} is : “.format(a,b))

print(subtraction(a,b))

print(“multiplicationof {0} & {1} is : “.format(a,b))

print(multiplication(a,b))

print(“division of {0} & {1} is : “.format(a,b))

print(division(a,b))

Question14. Write a program to swap two numbers using a third variable.

Answer:

first_number=int(input(“Enter First Number: “))

second_number=int(input(“Enter Second Number: “))

def swap(first_number,second_number):

third_variable=first_number

first_number=second_number

second_number=third_variable

returnfirst_number,second_number

print(swap(first_number,second_number))

Question 15. Write a program to swap two numbers without using a third variable.

Answer:

first_number=int(input(“Enter First Number: “))

second_number=int(input(“Enter Second Number: “))

def swap(first_number,second_number):

first_number,second_number=second_number,first_number

returnfirst_number,second_number

print(swap(first_number,second_number))

Question 16. Write a program to repeat the string ‘‘GOOD MORNING” n times. Here ‘n’ is an integer entered by the user.

Answer:

n=int(input(“Enter Number: “))

fori in range(n):

print(“GOOD MORINING “)

Question 17. Write a program to find average of three numbers.

Answer:

x=int(input(“Enter First Number: “))

y=int(input(“Enter Second Number: “))

z=int(input(“Enter Third Number: “))

def  average(x,y,z):

avg=x+y+z/3

returnavg

print(“Average : “)

print(average(x,y,z))

Question 18. The volume of a sphere with radius r is 4/3πr3. Write a Python program to find the volume of spheres with radius 7cm, 12cm, 16cm, respectively.

Answer:

defvolume_sphere(r):

pi=3.1415926535897931

volume=4.0/3.0*pi* r**3

return volume

print(“volume of spheres with radius 7cm”)

print(volume_sphere(7))

print(“volume of spheres with radius 12cm”)

print(volume_sphere(12))

print(“volume of spheres with radius 16cm”)

print(volume_sphere(16))

Question 19. Write a program that asks the user to enter their name and age. Print a message addressed to the user that tells the user the year in which they will turn 100 years old.

Answer:

fromdatetime import datetime

name = input(‘Name \n’)

age = int(input(‘Age  \n’))

defhundred_year(age):

hundred = int((100-age) + datetime.now().year)

return hundred

x=hundred_year(age)

print (‘Hello %s.  You will turn 100 years old in %s.’ % (name,x))

Question 20. The formula E = mc2 states that the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light (c = about 3×108 m/s) squared. Write a program that accepts the mass of an object and determines its energy.

Answer:

m=int(input(“Enter Mass in Kg: “))

def Einstein(m):

c=299792458

e= m*c**2

return e

print(“Equivalent energy (E): “)

print(Einstein(m))

Question 21. Presume that a ladder is put upright against a wall. Let variables length and angle store the length of the ladder and the angle that it forms with the ground as it leans against the wall. Write a Python program to compute the height reached by the ladder on the wall for the following values of length and angle:

a)16 feet and 75 degrees

b)20 feet and 0 degrees

c)24 feet and 45 degrees

d)24 feet and 80 degrees

Answer:

import math

defheight_reched(length,degrees):

radian=math.radians(degrees)

sin=math.sin(radian)

height=round(length*sin,2)

return height

print(” height reached by the ladder on the wall for the  length is 16 feet and 75 degrees “)

print(height_reched(16,75))

print(” height reached by the ladder on the wall for the  length is 20 feet and 0 degrees “)

print(height_reched(20,0))

print(” height reached by the ladder on the wall for the  length is 24 feet and 45 degrees “)

print(height_reched(24,45))

print(” height reached by the ladder on the wall for the  length is 24 feet and 80 degrees “)

print(height_reched(24,80))