NCERT solutions for Maths Rational Numbers

NCERT Solutions for Class 7 Maths Rational Numbers
Class –VII Mathematics (Ex. 9.1)
Question 1.List five rational numbers between:
(i) –1 and 0
(ii) –2 and –1
(iii) 5–4 and 3–2
(iv) 2–1 and 32
Answer:
(i) –1 and 0
Let us write –1 and 0 as rational numbers with denominator 6.
⇒ –1=6–6 and 0 = 60
∴ 6–6<6–5<6–4<6–3<6–2<6–1<0
⇒ –1<6–5<3–2<2–1<3–1<6–1<0
Therefore, five rational numbers between –1 and 0 would be
6–5,3–2,2–1,3–1,6–1
(ii) –2 and –1
Let us write –2 and –1 as rational numbers with denominator 6.
⇒ –2=6–12 and –1=6–6
∴ 6–12<6–11<6–10<6–9<6–8<6–7<6–6
⇒ –2<6–11<3–5<2–3<3–4<6–7<–1
Therefore, five rational numbers between –2 and –1 would be
6–11,3–5,2–3,3–4,6–7
(iii) 5–4 and 3–2
Let us write 5–4 and 3–2 as rational numbers with the same denominators.
⇒ 5–4=45–36 and 3–2=45–30
∴ 45–36<45–35<45–34<45–33<45–32<45–31<45–30
⇒ 5–4<9–7<45–34<15–11<45–32<45–31<3–2
Therefore, five rational numbers between 5–4 and 3–2 would be
9–7,45–34,15–11,45–32,45–31,3–2
(iv) 2–1 and 32
Let us write 2–1 and 32 as rational numbers with the same denominators.
⇒ 2–1=6–3 and 32=64
∴ 6–3<6–2<6–1<0<61<62<63<64
⇒ 2–1<3–1<6–1<0<61<31<21<32
Therefore, five rational numbers between 2–1 and 32 would be 3–1,6–1,0,61,31.
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 2.Write four more rational numbers in each of the following patterns:
(i) 5–3,10–6,15–9,20–12,………
(ii) 4–1,8–2,12–3,……….
(iii) 6–1,–122,–183,–244,………
(iv) 3–2,–32,–64,–96,……….
Answer:
(i) 5–3,10–6,15–9,20–12,………
⇒ 5×1–3×1,5×2–3×2,5×3–3×3,5×4–3×4,………
Therefore, the next four rational numbers of this pattern would be
5×5–3×5,5×6–3×6,5×7–3×7,5×8–3×8 = 25–15,30–18,35–21,40–24
(ii) 4–1,8–2,12–3,……….
⇒ 4×1–1×1,4×2–1×2,4×3–1×3,……….
Therefore, the next four rational numbers of this pattern would be
4×4–1×4,4×5–1×5,4×6–1×6,4×7–1×7 = 16–4,20–5,24–6,28–7
(iii) 6–1,–122,–183,–244,………
⇒ 6×1–1×1,–6×21×2,–6×31×3,–6×41×4,………
Therefore, the next four rational numbers of this pattern would be
–6×51×5,–6×61×6,–6×71×7,–6×81×8 = –305,–366,–427,–488
(iv) 3–2,–32,–64,–96,……….
⇒ 3×1–2×1,–3×12×1,–3×22×2,–3×32×3,……….
Therefore, the next four rational numbers of this pattern would be
–3×42×4,–3×52×5,–3×62×6,–3×72×7 = –128,–1510,–1812,–2114
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 3.Give four rational numbers equivalent to:
(i) 7–2
(ii) –35
(iii) 94
Answer:
(i) 7–2
7×2–2×2=14–4,7×3–2×3=21–6,7×4–2×4=28–8,7×5–2×5=35–10
Therefore, four equivalent rational numbers are 14–4,21–6,28–8,35–10.
(ii) –35
–3×25×2=–610,–3×35×3=–915,–3×45×4=–1220,–3×55×5=–1525
Therefore, four equivalent rational numbers are –610,–915,–1220,–1525.
(iii) 94
9×24×2=188,9×34×3=2712,9×44×4=3616,9×54×5=4520
Therefore, four equivalent rational numbers are 188,2712,3616,4520.
Question 4.Draw the number line and represent the following rational numbers on it:
(i) 43
(ii) 8–5
(iii) 4–7
(iv) 87
Answer:
(i) 43

(ii) 8–5

(iii) 4–7

(iv) 87

NCERT Solutions for Class 7 Maths Exercise 9.1
Question 5.The points P, Q, R, S, T, U, A and B on the number line are such that, TR = RS = SU and AP = PQ = QB. Name the rational numbers represented by P, Q, R and S.

Answer:
Each part which is between the two numbers is divided into 3 parts.
Therefore, A = 36, P = 37, Q = 38 and B = 39
Similarly T = 3–3, R = 3–4, S = 3–5 and U = 3–6
Thus, the rational numbers represented P, Q, R and S are 37,38,3–4 and 3–5 respectively.
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 6.Which of the following pairs represent the same rational numbers:
(i) 21–7 and 93
(ii) 20–16 and –2520
(iii) –3–2 and 32
(iv) 5–3 and 20–12
(v) –58 and 15–24
(vi) 31 and 9–1
(vii) –9–5 and –95
Answer:
(i) 21–7 and 93
⇒ 21–7 = 3–1 and 93 = 31 [Converting into lowest term]
∵ 3–1=31
∴ 21–7=93
(ii) 20–16 and –2520
⇒ 20–16 = 5–4 and –2520 = –54=5–4
[Converting into lowest term]
∵ 5–4 = 5–4
∴ 20–16 = –2520
(iii) –3–2 and 32
⇒ –3–2 = 32 and 32 = 32 [Converting into lowest term]
∵ 32 = 32
∴ –3–2 = 32
(iv) 5–3 and 20–12
⇒ 5–3 = 5–3 and 20–12 = 5–3 [Converting into lowest term]
∵ 5–3 = 5–3
∴ 5–3 = 20–12
(v) –58 and 15–24
⇒ –58 = 5–8 and 15–24 = 5–8 [Converting into lowest term]
∵ 5–8 = 5–8
∴ –58 = 15–24
(vi) 31 and 9–1
⇒ 31 = 31 and 9–1 = 9–1 [Converting into lowest term]
∵ 31=9–1
∴ 31=9–1
(vii) –9–5 and –95
⇒ –9–5 = 95 and –95 = 95 [Converting into lowest term]
∵ 95=–95
∴ –9–5=–95
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 7.Rewrite the following rational numbers in the simplest form:
(i) 6–8
(ii) 4525
(iii) 72–44
(iv) 10–8
Answer:
(i) 6–8 = 6÷2–8÷2 = 3–4 [H.C.F. of 8 and 6 is 2]
(ii)4525 = 45÷525÷5 = 95
[H.C.F. of 25 and 45 is 5]
(iii)72–44 = 72÷4–44÷4 = 18–11 [H.C.F. of 44 and 72 is 4]
(iv) 10–8 = 10÷2–8÷2 = 5–4 [H.C.F. of 8 and 10 is 2]
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 8.Fill in the boxes with the correct symbol out of <, > and =:
(i) 7–5 32
(ii) 5–4 7–5
(iii) 8–7 –1614
(iv) 5–8 4–7
(v) –31 4–1
(vi) –115 11–5
(vii) 0 6–7
Answer:
(i) 7–5 < 32 Since, the positive number if greater than negative number.
(ii) 5×7–4×7 7×5–5×5 ⇒ 35–28 < 35–25 ⇒ 5–4 < 7–5
(iii) 8×2–7×2 –16×(–1)14×(–1) ⇒ 16–14 = 16–14 ⇒8–7 = –1614
(iv) 5×4–8×4 4×5–7×5 ⇒ 20–32 > 20–35 ⇒ 5–8 > 4–7
(v) –31 4–1 ⇒–31 < 4–1
(vi) –115 11–5 ⇒–115 = 11–5
(vii) 0 > 6–7 Since, 0 is greater than every negative number.
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 9.Which is greater in each of the following:
(i) 32,25
(ii) 6–5,3–4
(iii) 4–3,–32
(iv) 4–1,41
(v) –372,–354
Answer:
(i) 3×22×2=64 and 2×35×3=615
Since 64 < 615
Therefore 32 < 25
(ii) 6×1–5×1=6–5 and 3×2–4×2=6–8
Since 6–5 > 6–8 Therefore 6–5 > 3–4
(iii) 4×3–3×3=12–9 and –3×(–4)2×(–4)=12–8
Since 12–9 < 12–8
Therefore 4–3 < –32
(iv) 4–1 < 41 Since positive number is always greater than negative number.
(v) –372=7–23=7×5–23×5=35–115 and –354=5–19=5×7–19×7=35–133
Since 35–115 > 35–133
Therefore–372 > –354
NCERT Solutions for Class 7 Maths Exercise 9.1
Question 10.Write the following rational numbers in ascending order:
(i) 5–3,5–2,5–1
(ii) 31,9–2,3–4
(iii) 7–3,2–3,4–3
Answer:
(i) 5–3,5–2,5–1⇒ 5–3<5–2<5–1
(ii) 31,9–2,3–4 ⇒93,9–2,9–12 [Converting into same denominator]
Now 9–12<9–2<93 ⇒ 3–4<9–2<31
(iii) 7–3,2–3,4–3
⇒ 2–3<4–3<7–3