Well-designed AP 7th Class Maths Guide Chapter 8 Rational Numbers Exercise 8.1 offers step-by-step explanations to help students understand problem-solving strategies.
Rational Numbers Class 7 Exercise 8.1 Solutions – 7th Class Maths 8.1 Exercise Solutions
Question 1.
List five rational numbers between:
i) -1 and 0
Solution:
\(\frac { -1 }{ 2 }\), \(\frac { -1 }{ 3 }\), \(\frac { -2 }{ 5 }\), \(\frac { -2 }{ 3 }\), \(\frac { -2 }{ 7 }\)
ii) -2 and -1
Solution:
\(\frac { -3 }{ 2 }\), \(\frac { -5 }{ 3 }\), \(\frac { -8 }{ 5 }\), \(\frac { -10 }{ 7 }\), \(\frac { -9 }{ 5 }\)
iii) \(\frac { -4 }{ 5 }\) and \(\frac { -2 }{ 3 }\)
Solution:
\(\frac { -4 }{ 5 }\) and \(\frac { -2 }{ 3 }\) converting into like fractions, we get
\(\frac { -4 }{ 5 }\) = \(\frac{(-4 \times 9)}{(5 \times 9)}\) = \(\frac { -36 }{ 45 }\)
\(\frac { -2 }{ 3 }\) = \(\frac{(-2 \times 13)}{(3 \times 15)}\) = \(\frac { -30 }{ 45 }\)
Five rational numbers between \(\frac { -4 }{ 5 }\) and \(\frac { -2 }{ 3 }\) are,
\(\frac { -36 }{ 45 }\) < \(\frac { -35 }{ 45 }\) < \(\frac { -34 }{ 45 }\) < \(\frac { -33 }{ 45 }\) < \(\frac { -31 }{ 45 }\) < \(\frac { -30 }{ 45 }\)
\(\frac { -4 }{ 5 }\) < \(\frac { -35 }{ 45 }\) < \(\frac { -34 }{ 45 }\) < \(\frac { -33 }{ 45 }\) < \(\frac { -32 }{ 45 }\) < \(\frac { -31 }{ 45 }\) < \(\frac { -2 }{ 3 }\)
Thus, the five rational numbers between \(\frac{-4}{5}\) and \(\frac{-2}{3}\) are,
\(\frac { -7 }{ 9 }\), \(\frac { -34 }{ 45 }\), \(\frac { -11 }{ 15 }\), \(\frac { -32 }{ 45 }\), \(\frac { -31 }{ 45 }\)
iv) –\(\frac { 1 }{ 2 }\) and \(\frac { 2 }{ 3 }\)
Solution:
\(\frac { -1 }{ 2 }\) × \(\frac { 3 }{ 3 }\) and \(\frac { 2 }{ 3 }\) × \(\frac { 2 }{ 2 }\) = \(\frac { -3 }{ 6 }\) and \(\frac { 4 }{ 6 }\)
The five rational numbers are
\(\frac { 3 }{ 6 }\), \(\frac { 2 }{ 6 }\), \(\frac { 1 }{ 6 }\), 0, \(\frac { -1 }{ 6 }\) i.e., \(\frac { 1 }{ 2 }\), \(\frac { 1 }{ 3 }\), \(\frac { 1 }{ 6 }\), 0, \(\frac { -1 }{ 6 }\)
Question 2.
Write four more rational numbers in each of the following patterns.
i) \(\frac { -3 }{ 5 }\), \(\frac { -6 }{ 10 }\), \(\frac { -9 }{ 15 }\), \(\frac { -12 }{ 20 }\), ……………..
Solution:
\(\frac { -3 }{ 5 }\), \(\frac { -6 }{ 10 }\), \(\frac { -9 }{ 15 }\), \(\frac { -12 }{ 20 }\)
\(\frac { -12 – 3 }{ 20 + 5 }\) = \(\frac { -15 }{ 25 }\) ⇒ \(\frac{-15-3}{25+5}\) = \(\frac{-18}{30}\)
\(\frac{-18-3}{30+5}\) = \(\frac { -21 }{ 35 }\) ⇒ \(\frac{-21-3}{35+5}\) = \(\frac { -24 }{ 40 }\)
∴ \(\frac { -3 }{ 5 }\), \(\frac { -6 }{ 10 }\), \(\frac { -9 }{ 15 }\), \(\frac { -12 }{ 20 }\), \(\frac { -15 }{ 25 }\), \(\frac { -18 }{ 30 }\), \(\frac { -21 }{ 35 }\), \(\frac { -24 }{ 40 }\)
ii) \(\frac { -1 }{ 4 }\), \(\frac { -2 }{ 8 }\), \(\frac { -3 }{ 12 }\), ……………..
Solution:
\(\frac { -1 }{ 4 }\), \(\frac { -2 }{ 8 }\), \(\frac { -3 }{ 12 }\), ……………..
\(\frac{-3-1}{12+4}\) = \(\frac { -4 }{ 16 }\)
\(\frac{-4-1}{16+4}\) = \(\frac{-5}{20}\)
\(\frac{-5-1}{20+4}\) = \(\frac{-6}{24}\)
\(\frac{-6-1}{24+4}\) = \(\frac{-7}{28}\)
∴ \(\frac{-1}{4}\), \(\frac{-2}{8}\), \(\frac{-3}{12}\), \(\frac{-4}{16}\), \(\frac{-5}{20}\), \(\frac{-6}{24}\), \(\frac{-7}{28}\)
iii) \(\frac { -1 }{ 6 }\), \(\frac { 2 }{ -12 }\), \(\frac { 3 }{ -18 }\), \(\frac { 4 }{ -24 }\) …………..
Solution:
\(\frac { -1 }{ 6 }\), \(\frac { 2 }{ -12 }\), \(\frac { 3 }{ -18 }\), \(\frac { 4 }{ -24 }\)
\(\frac { 4 + 1 }{ – 24 – 6 }\) = \(\frac { 5 }{ -30 }\); \(\frac { 5 + 1 }{ -30 – 6 }\) = \(\frac { 6 }{ -36 }\)
\(\frac { 6 + 1 }{ – 36 – 6 }\) = \(\frac { 7 }{ -42 }\); \(\frac { 7 + 1 }{ – 42 – 6 }\) = \(\frac { 8 }{ -48 }\)
∴ \(\frac { -1 }{ 6 }\), \(\frac { 2 }{ -12 }\), \(\frac { 3 }{ -18 }\), \(\frac { 4 }{ -24 }\), \(\frac { 5 }{ -30 }\), \(\frac { 6 }{ -36 }\), \(\frac { 7 }{ -42 }\), \(\frac { 8 }{ -48 }\)
iv) \(\frac { -2 }{ 3 }\), \(\frac { 2 }{ -3 }\), \(\frac { 4 }{ -6 }\), \(\frac { 6 }{ -9 }\), …………
Solution:
\(\frac { -2 }{ 3 }\), \(\frac { 2 }{ -3 }\), \(\frac { 4 }{ -6 }\), \(\frac { 6 }{ -9 }\), …………
\(\frac { 6 + 2 }{ – 9 – 3 }\) = \(\frac { 8 }{ -12 }\)
\(\frac { 8 + 2 }{ – 12 – 3 }\) = \(\frac { 10 }{ -15 }\)
\(\frac { 10 + 2 }{ – 15 – 3 }\) = \(\frac { 12 }{ -18 }\)
\(\frac { 12 + 2 }{ – 18 – 3 }\) = \(\frac { 14 }{ -21 }\)
∴ \(\frac { -2 }{ 3 }\), \(\frac { 2 }{ -3 }\), \(\frac { 4 }{ -6 }\), \(\frac { 6 }{ -9 }\), \(\frac { 8 }{ -21 }\), \(\frac { 10 }{ -15 }\), \(\frac { 12 }{ -18 }\), \(\frac { 14 }{ -21 }\)
Question 3.
Give four rational numbers equivalent to:
i) \(\frac { -2 }{ 7 }\)
Solution:
\(\frac { -2 }{ 7 }\) × \(\frac { 2 }{ 2 }\) = \(\frac { -4 }{ 14 }\)
\(\frac { -2 }{ 7 }\) × \(\frac { 3 }{ 3 }\) = \(\frac { -6 }{ 21 }\)
\(\frac { -2 }{ 7 }\) × \(\frac { 4 }{ 4 }\) = \(\frac { -8 }{ 28 }\)
\(\frac { -2 }{ 7 }\) × \(\frac { 5 }{ 5 }\) = \(\frac { -10 }{ 35 }\)
∴ The four rational numbers equivalent to \(\frac { -2 }{ 7 }\) are \(\frac { -4 }{ 14 }\), \(\frac { -6 }{ 21 }\), \(\frac { -8 }{ 28 }\), \(\frac { -10 }{ 35 }\).
ii) \(\frac { 5 }{ -3 }\)
Solution:
\(\frac { 5 }{ -3 }\) = \(\frac { -5 }{ 3 }\)
\(\frac { -5 }{ 3 }\) × \(\frac { 2 }{ 2 }\) = \(\frac { -10 }{ 6 }\)
\(\frac { -5 }{ 3 }\) × \(\frac { 3 }{ 3 }\) = \(\frac { -15 }{ 9 }\)
\(\frac { -5 }{ 3 }\) × \(\frac { 4 }{ 4 }\) = \(\frac { -20 }{ 12 }\)
\(\frac { -5 }{ 3 }\) × \(\frac { 5 }{ 5 }\) = \(\frac { -25 }{ 15 }\)
∴ The four rational numbers equivalent to \(\frac { -5 }{ 3 }\) are \(\frac { -10 }{ 6 }\), \(\frac { -15 }{ 9 }\), \(\frac { -20 }{ 12 }\), \(\frac { -25 }{ 15 }\)
iii) \(\frac { 4 }{ 9 }\)
Solution:
\(\frac { 4 }{ 9 }\) × \(\frac { 2 }{ 2 }\) = \(\frac { 8 }{ 18 }\)
\(\frac { 4 }{ 9 }\) × \(\frac { 3 }{ 3 }\) = \(\frac { 12 }{ 27 }\)
\(\frac { 4 }{ 9 }\) × \(\frac { 4 }{ 4 }\) = \(\frac { 16 }{ 36 }\)
\(\frac { 4 }{ 9 }\) × \(\frac { 5 }{ 5 }\) = \(\frac { 20 }{ 45 }\)
∴ The four rational numbers equivalent to \(\frac { 4 }{ 9 }\) are \(\frac { 8 }{ 18 }\), \(\frac { -12 }{ 27 }\), \(\frac { 16 }{ 36 }\), \(\frac { 20 }{ 45 }\).
Question 4.
Draw the number line and represent the following rational numbers on it:
Solution:
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.
Solution:
P represents \(\frac { 7 }{ 3 }\)
Q represents \(\frac { 8 }{ 3 }\)
R represents \(\frac { -4 }{ 3 }\)
S represents \(\frac { -5 }{ 3 }\)
Question 6.
Which of the following pairs represent the same rational number?
i) \(\frac { -7 }{ 21 }\) and \(\frac { 3 }{ 9 }\)
Solution:
\(\frac { -7 }{ 21 }\) and \(\frac { 3 }{ 9 }\)
Both are not same as one is negative and other is positive rational number.
ii) \(\frac { -16 }{ 20 }\) and \(\frac { 20 }{ -25 }\)
Solution:
\(\frac { -16 }{ 20 }\) and \(\frac { 20 }{ -25 }\) \(\frac { -16 }{ 20 }\)
= \(\frac { – 4 × 4 }{ 5 × 4 }\) = \(\frac { -4 }{ 5 }\)
\(\frac { 20 }{ -25 }\) = \(\frac { -20 }{ 25 }\)
= \(\frac { – 4 × 5 }{ 5 × 5 }\) = \(\frac { -4 }{ 5 }\)
∴ Both are same \(\frac { -16 }{ 20 }\) = \(\frac { 20 }{ -25 }\)
iii) \(\frac { -2 }{ -3 }\) and \(\frac { 2 }{ 3 }\)
Solution:
\(\frac { -2 }{ -3 }\) and \(\frac { 2 }{ 3 }\)
∴ Both are same \(\frac { -2 }{ -3 }\) and \(\frac { 2 }{ 3 }\)
iv) \(\frac { -3 }{ 5 }\) and \(\frac { -12 }{ 20 }\)
Solution:
\(\frac { -3 }{ 5 }\) and \(\frac { -12 }{ 20 }\)
\(\frac { -12 }{ 20 }\) = \(\frac{-4 \times 3}{5 \times 4}\) = \(\frac { -3 }{ 5 }\)
Both are same
v) \(\frac { 8 }{ -5 }\) and \(\frac { -24 }{ 15 }\)
Solution:
\(\frac { 8 }{ -5 }\) and \(\frac { -24 }{ 15 }\)
\(\frac { -24 }{ 15 }\) = \(\frac{-8 \times 3}{5 \times 3}\) = \(\frac { -8 }{ 5 }\)
\(\frac { 8 }{ -5 }\) = \(\frac { -8 }{ 5 }\) Both are same
vi) \(\frac { 1 }{ 3 }\) and \(\frac { -1 }{ 9 }\)
Solution:
\(\frac { 1 }{ 3 }\) and \(\frac { -1 }{ 9 }\)
Both are not same as one is negative and other is positive rational number.
vii) \(\frac { -5 }{ -9 }\) and \(\frac { 5 }{ -9 }\)
Solution:
\(\frac { -5 }{ -9 }\) and \(\frac { 5 }{ -9 }\)
\(\frac { -5 }{ -9 }\) ≠ \(\frac { 5 }{ -9 }\)
Both are not same as one is negative and other is positive rational number.
Question 7.
Rewrite the following rational numbers in the simplest form :
i) \(\frac { -8 }{ 6 }\)
Solution:
\(\frac { -8 }{ 6 }\) = \(\frac{-2 \times 2 \times 2}{2 \times 3}\) = \(\frac{-4}{3}\)
ii) \(\frac { 25 }{ 45 }\)
Solution:
\(\frac { 25 }{ 45 }\) = \(\frac{5 \times 5}{9 \times 5}\) = \(\frac { 5 }{ 9 }\)
iii) \(\frac { -44 }{ 72 }\)
Solution:
\(\frac { -44 }{ 72 }\) = \(\frac{-2 \times 2 \times 11}{2 \times 2 \times 3 \times 3}\) = \(\frac { -11 }{ 18 }\)
iv) \(\frac { -8 }{ 10 }\)
Solution:
\(\frac { -8 }{ 10 }\) = \(\frac{-2 \times 4}{2 \times 5}\) = \(\frac { -4 }{ 5 }\)
Question 8.
Fill in the boxes with the correct symbol out of >, <, and =
Negative rational number is always less than a positive rational number.
The number ‘ 0 ‘ is always greater than a negative rational number. (Or)
‘0’ lies to the right of \(\frac{-7}{6}\) on number line, so ‘ 0 ‘ is greater than (>) \(\frac{-7}{6}\).
Question 9.
Which is greater in each of the following :
i) \(\frac{2}{3}\), \(\frac{5}{2}\)
Solution:
\(\frac{2}{3}\), \(\frac{5}{2}\)
\(\frac{2}{3}\) × \(\frac{2}{2}\), \(\frac{5}{2}\) × \(\frac{3}{3}\)
\(\frac{4}{6}\), \(\frac{15}{6}\)
\(\frac{15}{6}\) > \(\frac{4}{6}\)
\(\frac{5}{2}\) > \(\frac{2}{3}\)
ii) \(\frac{-5}{6}\), \(\frac{-4}{3}\)
Solution:
\(\frac{-5}{6}\), \(\frac{-4}{3}\)
\(\frac{-4}{3}\) × \(\frac{2}{2}\) = \(\frac{-8}{6}\)
\(\frac{-5}{6}\) > \(\frac{-8}{6}\)
∴ \(\frac{-5}{6}\) > \(\frac{-4}{3}\)
iii) \(\frac{-3}{4}\), \(\frac{2}{-3}\)
Solution:
\(\frac{-3}{4}\), \(\frac{2}{-3}\)
\(\frac{2}{-3}\) × \(\frac{3}{3}\) = \(\frac{-9}{12}\)
\(\frac{-9}{12}\) < \(\frac{-8}{12}\)
\(\frac{2}{-3}\) > \(\frac{-3}{4}\)
iv) \(\frac{-1}{4}\), \(\frac{1}{4}\)
Solution:
\(\frac{-1}{4}\), \(\frac{1}{4}\)
v) -3\(\frac{2}{7}\), -3\(\frac{4}{5}\)
Solution:
-3\(\frac{2}{7}\), -3\(\frac{4}{5}\)
\(\frac{-23}{7}\), \(\frac{-19}{5}\)
\(\frac{-23}{7}\) × \(\frac{5}{5}\)
\(\frac{-19}{5}\) × \(\frac{7}{7}\)
\(\frac{-115}{35}\) × \(\frac{-133}{35}\)
\(\frac{-115}{35}\) > \(\frac{-133}{35}\)
∴ -3\(\frac{2}{7}\) > -3\(\frac{4}{5}\)
Question 10.
Write the following rational numbers in ascending order :
i) \(\frac{-3}{5}\), \(\frac{-2}{5}\), \(\frac{-1}{5}\)
Solution:
\(\frac{-3}{5}\), \(\frac{-2}{5}\), \(\frac{-1}{5}\)
\(\frac{-3}{5}\) < \(\frac{-2}{5}\) < \(\frac{-1}{5}\)
ii) \(\frac{-1}{3}\), \(\frac{-2}{9}\), \(\frac{-4}{3}\)
Solution:
\(\frac{-1}{3}\), \(\frac{-2}{9}\), \(\frac{-4}{3}\)
\(\frac{-1}{3}\) × \(\frac{3}{3}\), \(\frac{-2}{9}\), \(\frac{-4}{3}\) × \(\frac{3}{3}\)
\(\frac{-3}{9}\), \(\frac{-2}{9}\), \(\frac{-12}{9}\)
\(\frac{-12}{9}\) < \(\frac{-3}{9}\) < \(\frac{-2}{9}\)
\(\frac{-4}{3}\) < \(\frac{-1}{3}\) < \(\frac{-2}{9}\)
iii) \(\frac{-3}{7}\), \(\frac{-3}{2}\), \(\frac{-3}{4}\)
Solution:
\(\frac{-3}{7}\), \(\frac{-3}{2}\), \(\frac{-3}{4}\)
LCM of 2, 4, 7 is 28
\(\frac{-3}{7}\) × \(\frac{4}{4}\), \(\frac{-3}{2}\) × \(\frac{14}{14}\), \(\frac{-3}{4}\) × \(\frac{7}{7}\)
\(\frac{-12}{28}\), \(\frac{-42}{28}\), \(\frac{-21}{28}\)
\(\frac{-42}{28}\) < \(\frac{-21}{28}\) < \(\frac{-12}{28}\)
\(\frac{-3}{2}\) < \(\frac{-3}{4}\) < \(\frac{-3}{7}\)