NCERT Class 6 Mathematics Eleventh Chapter Algebra Exercise 11.4 Solution

NCERT Class 6 Mathematics Eleventh Chapter Algebra Exercise 11.4 Solution

EXERCISE 11.4

(1) Answer the following:

(a) Take Sarita’s present age to be y years

(i) What will be her age 5 years from now?

Ans: (y + 5) years

(ii) What was her age 3 years back?

Ans: (y – 3) years

(iii) Sarita’s grandfather is 6 times her age. What is the age of her grandfather?

Ans: 6y years.

(iv) Grandmother is 2 years younger than grandfather. What is grandmother’s age?

Ans: (6y – 2) years

(v) Sarita’s father’s age is 5 years more than 3 times Sarita’s age. What is her father’s age?

Ans: (3y + 5) years.

(b) The length of a rectangular hall is 4 meters less than 3 times the breadth of the hall. What is the length, if the breadth is b meters?

Solution: The breadth of the hall is b meters.

Therefore, the length of the hall = (3b – 4) meters.

(c) A rectangular box has height h cm. Its length is 5 times the height and breadth is 10 cm less than the length. Express the length and the breadth of the box in terms of the height.

Solution: The height of rectangular box is h cm.

The length of the rectangular box = 5h cm

The breadth of the box = (5h – 10) cm.

(d) Meena, Beena and Leena are climbing the steps to the hill top. Meena is at step s, Beena is 8 steps ahead and Leena 7 steps behind. Where are Beena and Meena? The total number of steps to the hill top is 10 less than 4 times what Meena has reached. Express the total number of steps using s.

Solution: Here, Meena is at step = s

Beena is step = (s + 8)

Leena is step = (s – 7)

The total number of step to hill top = (4s – 10)

(e) A bus travels at v km per hour. It is going from Daspur to Beespur. After the bus has travelled 5 hours, Beespur is still 20 km away. What is the distance from Daspur to Beespur? Express it using v.

Solution: The bus travels in one hour v km.

After 5 hours the bus travel = 5v km

Therefore, the distance is Daspur to Beesour = (5v + 20) km

(2) Change the following statements using expressions into statements in ordinary language. (For example, Given Salim scores r runs in a cricket match, Nalin scores (r + 15) runs. In ordinary language – Nalin scores 15 runs more than Salim.)

(a) A notebook costs Rs p. A book costs Rs 3p.

Solution: A book costs 3 time more a notebook costs.

(b) Tony puts q marbles on the table. He has 8q marbles in his box.

Solution: Tony’s box contain 8 times marbles which he put on the table.

(c) Our class has n students. The school has 20 n students.

Solution: Total number of students in the school 20 time that of our class.

(d) Jaggu is z years old. His uncle is 4 z years old and his aunt is (4z – 3) years old.

Solution: Jaggu’s uncle is 4 times older than Jaggu and Jaggu’s aunt is 3 years younger than his uncle.

(e) In an arrangement of dots there are r rows. Each row contains 5 dots.

Solution: The total number of dots is 5 times the number of rows.

(3) (a) Given Munnu’s age to be x years, can you guess what (x – 2) may show? (Hint : Think of Munnu’s younger brother.) Can you guess what (x + 4) may show? What (3x + 7) may show?

Solution: 2 years ago Munnu’s age was (x – 2) years.

Or, Munnu’s bother is 2 years younger than Munnu.

After 4 years Munnu’s age will be (x + 4) years.

(3x + 7) = Munnu’s  mother is 7 more than 3 times of Munnu’s age.