Exercise 11.4
Q 1 Part "A" - Ex 11.4 - Algebra - NCERT Maths Class 6th - Chapter 11
Q 1 Part "B" - Ex 11.4 - Algebra - NCERT Maths Class 6th - Chapter 11
Q 1 Part "C" & "D" - Ex 11.4 - Algebra - NCERT Maths Class 6th - Chapter 11
Page No 235:
Question 1:
Answer the following:(a) Take Sarita’s present age to be y years
(i) What will be her age 5 years from now?
(ii) What was her age 3 years back?
(iii) Sarita’s grandfather is 6 times her age. What is the age of her grandfather?
(iv) Grandmother is 2 years younger than grandfather. What is grandmother’s age?
(v) Sarita’s father’s age is 5 years more than 3 times Sarita’s age. What is her father’s age?
(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?
(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.
(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.
(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.
Answer:
(a) (i) Sarita’s age after 5 years from now = Sarita’s present age + 5= y + 5
(ii) 3 years ago, Sarita’s age = Sarita’s present age − 3
= y − 3
(iii) Grandfather’s age = 6 × Sarita’s present age = 6y
(iv) Grandmother’s age = Grandfather’s present age − 2 = 6y − 2
(v) Father’s age = 5 + 3 × Sarita’s present age = 5 + 3y
(b) Length = 3 × Breadth − 4
l = (3b − 4) metres
(c) Length = 5 × Height
l = 5h cm
Breadth = 5 × Height − 10
b = (5h − 10) cm
(d) Step at which Beena is = (Step at which Meena is) + 8
= s + 8
Step at which leena is = (Step at which Meena is) − 7
= s − 7
Total steps = 4 × (Step at which Meena is) − 10 = 4s − 10
(e) Speed = v km/hr
Distance travelled in 5 hrs = 5 × v = 5v km
Total distance between Daspur and Beespur = (5v + 20) km
Q 2 - Ex 11.4 - Algebra - NCERT Maths Class 6th - Chapter 11
Page No 236:
Question 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 note book costs Rs p. A book costs Rs 3 p.
(b) Tony puts q marbles on the table. He has 8 q marbles in his box.
(c) Our class has n students. The school has 20 n students.
(d) Jaggu is z years old. His uncle is 4 z years old and his aunt is (4z − 3) years old.
(e) In an arrangement of dots there are r rows. Each row contains 5 dots.
Answer:
(a) A book costs three times the cost of a notebook.(b) Tony’s box contains 8 times the number of marbles on the table.
(c) Total number of students in the school is 20 times that of our class.
(d) Jaggu’s uncle is 4 times older than Jaggu and Jaggu’s aunt is 3 years younger than his uncle.
(e) The total number of dots is 5 times the number of rows.
Q 3 - Ex 11.4 - Algebra - NCERT Maths Class 6th - Chapter 11
Question 3:
(a) Given Munnu’s age to be x years, can you guess what (x − 2) may show?(Hint: Think of Mannu’s younger brother.)
Can you guess what (x + 4) may show? What (3x + 7) may show?
(b) Given Sara’s age today to be y years. Think of her age in the future or in the past.
What will the following expression indicate?
(c) Given n students in the class like football, what may 2n show? What may
show? (Hint: Think of games other than football).Answer:
(a)(x − 2) represents that the person, whose age is (x − 2) years, is 2 years younger to Munnu.(x + 4) represents that the person, whose age is (x + 4) years, is 4 years elder to Munnu.
(3x + 7) represents that the person, whose age is (3x + 7) years, is elder to Munnu and his age is 7 years more than three times of the age of Munnu.
(b) In future
After n years from now, Sara’s age will be (y + n) years.
In past
n years ago, Sara’s age was (y − n) years.
(y + 7) represents that the person, whose age is (y + 7) years, is 7 years elder to Sara.
(y − 3) represents that the person, whose age is (y − 3) years, is 3 years younger to Sara.
(y +
) represents that the person, whose age is (y + ) years, is years elder to Sara.(y −
) represents that the person, whose age is (y − ) years, is years younger to Sara.(c) 2n may represent the number of students who like either football or some other game such as cricket whereas
represents the number of students who like cricket, out of the total number of students who like football.
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