# NCERT Solutions Class 11 Computer Science Chapter 4 Introduction to Problem Solving

## NCERT Solutions Class 11 Computer Science Chapter 4 Introduction to Problem Solving

NCERT Solutions Class 11 Computer Science Chapter 4 Introduction to Problem Solving: National Council of Educational Research and Training Class 11 Computer Science Chapter 4 Solutions – Introduction to Problem Solving. NCERT Solutions Class 11 Computer Science Chapter 4 PDF Download.

### NCERT Solutions Class 11 Computer Science Chapter 4: Overview

 Board NCERT Class 11 Subject Computer Science Chapter 4 Chapter Name Introduction to Problem Solving Topic Exercise Solutions

### NCERT Solutions Class 11 Computer Science Chapter 4 Introduction to Problem Solving

Question 3. Write the pseudocode to print all multiples of 5 between 10 and 25 (including both 10 and 25).

FOR EACH I := 10 TO 15

IF I % 5 :=0   THEN

PRINT   I

END IF

END LOOP

Question 4. Give an example of a loop that is to be executed a certain number of times.

Answer: Suppose we certain number starting from 11 to 16. The loop will be executed as follow:

SET i: = 11

FOR i: = 11 to 16 do

PRINT i

END LOOP

Question 5. Suppose you are collecting money for something. You need ` 200 in all. You ask your parents, uncles and aunts as well as grandparents. Different people may give either ` 10, ` 20 or even ` 50. You will collect till the total becomes 200. Write the algorithm.

Step 1: Set need Money := 0

Step 2: While Loop (need Money <200)

Do

Input money

Step 3: need Money : = need Money + money

Step 4: End Loop

Question 6. Write the pseudocode to print the bill depending upon the price and quantity of an item. Also print Bill GST, which is the bill after adding 5% of tax in the total bill.

INPUT all_Item

INPUT price_for_each_Item

COMPUTE bill :=totalItem * price_for_each_Item

PRINT bill

COMPUTE tax := bill * (5 / 100)

COMPUTE bill_with_gst := bill + tax

PRINT bill_with_gst

Question 7. Write pseudocode that will perform the following: a) Read the marks of three subjects: Computer Science, Mathematics and Physics, out of 100 b) Calculate the aggregate marks c) Calculate the percentage of marks.

INPUT Computer_Science, maths, physics

COMPUTE aggregate := (Computer_Science + maths + physics) / 3

COMPUTE percentage := ((Computer_Science + math + physics) / 300) * 100

PRINT aggregate

PRINT percentage

Question8. Write an algorithm to find the greatest among two different numbers entered by the user.

Step3:IF (num1 > num2)

PRINT num1

ELSE

PRINT num2

Step4: END

Question9. Write an algorithm that performs the following: Ask a user to enter a number. If the number is between 5 and 15, write the word GREEN. If the number is between 15 and 25, write the word BLUE. if the number is between 25 and 35, write the word ORANGE. If it is any other number, write that ALL COLOURS ARE BEAUTIFUL.

Step 1: INPUT n

Step 2: IF n>5 And n<15 THEN

Step 3: PRINT “GREEN”

Step 4: ELSE IF n>15 And n<225 THEN

Step 5: PRINT “BLUE”

Step 6: ELSE IF n>25 And n<35 THEN

Step 7: PRINT “ORANGE”

Step 8: ELSE

PRINT “ALL COLOURS ARE BEAUTIFUL”

Step 9: End IF

Question 10. Write an algorithm that accepts four numbers as input and find the largest and smallest of them.

Question11. Write an algorithm to display the total water bill charges of the month depending upon the number of units consumed by the customer as per the following criteria:

• for the first 100 units @ 5 per unit
• for next 150 units @ 10 per unit
• more than 250 units @ 20 per unit Also add meter charges of 75 per month to calculate the total water bill .

Step 1: INPUT units

Setp 2: SET bill := 0

Step 3: IF units > 250 THEN

COMPUTE bill := units * 20

ELSE

IF units <= 100 THEN

COMPUTE bill := units * 5

ELSE

COMPUTE bill := 100 * 5 + (units – 100) * 10

END IF

Step 4: END IF

Step 5: COMPUTE total_Bill := bill + 75

Step 6: PRINT total_Bil

Question 12. What are conditionals? When they are required in a program?

In programming conditionals are used for providing the condition to values, input and output. There are various conditional statements are there to evaluate the expression. Generally conditional statement give us a output in the form of true or false which is known as Boolean value.

Conditionals are required in program to check whether the value is satisfied with required output or not.

Question 13. Match the pairs Question14. Following is an algorithm for going to school or college. Can you suggest improvements in this to include other options?

Reach_School_Algorithm

a) Wake up

c) Take lunch box

d) Take bus

e) Get off the bus

f) Reach school or college

1. Wake up
2. Brush our teeth
3. Do some exercise
4. Take a bath
6. Take a breakfast
7. Take a lunch box
8. Go to bus stand
9. Take a bus
10. Get off the bus
11. Reach school or college

Question 15. Write a pseudocode to calculate the factorial of a number (Hint: Factorial of 5, written as 5!=5 4 3 21 ×××× )

INPUT number

SET factorial := 1, i := 1

WHILE i<= number DO

COMPUTE factorial := factorial * i

INCREASE i by 1

END LOOP

PRINT factorial

Question 16. Draw a flowchart to check whether a given number is an Armstrong number. An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number since 3**3 + 7**3 + 1**3 = 371. Question 17. Following is an algorithm to classify numbers as “Single Digit”, “Double Digit” or “Big”. Classify_Numbers_Algo

INPUT Number

IF Number < 9

“Single Digit”

Else If Number < 99

“Double Digit”

Else

“Big”

Verify for (5, 9, 47, 99, 100 200) and correct the algorithm if required.

For given data,

5 and 9 are single digit number, so it will print “single digit”

47 and 99 are double digit number, so it will print “double digit”

100 and 200 is a three digit number, so it will print “big”

Correct algorithm:

Step 1: INPUT Number

Step 2: IF Number <= 9

“Single Digit”

Step 3: Else If Number <= 99

“Double Digit”

Step 4: Else

“Big”

Step 5: End IF

Question 18. For some calculations, we want an algorithm that accepts only positive integers upto 100.Accept_1to100_Algo

INPUT Number

IF (0<= Number) AND (Number <= 100)

ACCEPT

Else

REJECT

a) On what values will this algorithm fail?

b) Can you improve the algorithm?

a) On what values will this algorithm fail?

This algorithm fails at value 0. Because in condition we specify “greater than equal to operator”. So it will accept zero also.

b) Can you improve the algorithm?

Correct algorithm:

INPUT Number

IF (0<Number) AND (Number <= 100)

ACCEPT

Else

REJECT

Updated: May 5, 2021 — 11:14 pm