The World of Numbers | Exercise 3.4

Question 2

Find three distinct rational numbers that lie strictly between 12-\frac{1}{2} and 14\frac{1}{4}.

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Solution

We need to find three rational numbers that are strictly between the given numbers.

Step 1 — Find a common denominator

Let's write down the given rational numbers. They are 12-\frac{1}{2} and 14\frac{1}{4}. We need to find a common denominator for 2 and 4. The least common multiple of 2 and 4 is 4. Now, we convert 12-\frac{1}{2} to a fraction with denominator 4.

12=1×22×2-\frac{1}{2} = -\frac{1 \times 2}{2 \times 2}

24\boxed{-\frac{2}{4}}

The other number, 14\frac{1}{4}, already has a denominator of 4.

Diagram 1

Step 2 — Identify numbers between them

We need numbers strictly between 24-\frac{2}{4} and 14\frac{1}{4}. We can look at the numerators -2 and 1. The integers between -2 and 1 are -1 and 0. So, two rational numbers are 14-\frac{1}{4} and 04\frac{0}{4}. 04\frac{0}{4} simplifies to 0. We still need to find one more distinct rational number. To find more numbers, we can use a larger common denominator. Let's multiply both fractions by 22\frac{2}{2}. This will change the denominator to 8.

24=2×24×2-\frac{2}{4} = -\frac{2 \times 2}{4 \times 2}

=48= -\frac{4}{8}

14=1×24×2\frac{1}{4} = \frac{1 \times 2}{4 \times 2}

=28= \frac{2}{8}

Now we need numbers strictly between 48-\frac{4}{8} and 28\frac{2}{8}. We can choose from numbers like 38-\frac{3}{8}, 28-\frac{2}{8}, 18-\frac{1}{8}, 08\frac{0}{8}, 18\frac{1}{8}. Let's pick three distinct numbers from this list. We can choose 14-\frac{1}{4}, 0, and 18\frac{1}{8}. Remember that 14-\frac{1}{4} is the same as 28-\frac{2}{8}. Also, 0 is the same as 08\frac{0}{8}. These three numbers are all strictly between 12-\frac{1}{2} and 14\frac{1}{4}.

Answer

(i) 14-\frac{1}{4} (ii) 00 (iii) 18\frac{1}{8}

More questions in Exercise 3.4

Q1

Represent the rational numbers 23\frac{2}{3}, 54-\frac{5}{4} and 1121\frac{1}{2} on a single number line.

Q2

Find three distinct rational numbers that lie strictly between 12-\frac{1}{2} and 14\frac{1}{4}.

Q3

Simplify the expression: (14)+(512)\left(-\frac{1}{4}\right) + \left(\frac{5}{12}\right).

Q4

A tailor has 153415\frac{3}{4} metres of fine silk. If making one kurta requires 2142\frac{1}{4} metres of silk, exactly how many kurtas can he make?

Q5

Find three rational numbers between 3.1415 and 3.1416.

Q6

Can you think of other way(s) to find a rational number between any two rational numbers?

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