JKBOSE Class 3rd Math Chapter 4 (Long and Short) complete solved exercises, measurement concept questions, centimetre vs metre conversions, and revision notes according to the latest Jammu & Kashmir Board curriculum.
📌 Key Concepts
- Standard Units of Length: Understanding Centimetre (cm), Metre (m), and Kilometre (km).
- Conversion Rule: $1\text{ metre (m)} = 100\text{ centimetres (cm)}$ and $1\text{ kilometre (km)} = 1000\text{ metres (m)}$.
- Using a Ruler: Reading scale markings starting from 0 cm instead of 1 cm.
- Unit Choice: Deciding whether an object should be measured in centimetres, metres, or kilometres.
Exercise Questions & Answers
Q1 Which of these will be measured in Centimetres (cm) and which in Metres (m)?
1. Width of a computer screen: Centimetres (cm)
2. Length of a Pagri worn by Sikhs: Metres (m)
3. Height of a 1-year old child: Centimetres (cm)
4. Length of a banana: Centimetres (cm)
5. Waist of an elephant: Metres (m)
6. Height of a sugarcane: Metres (m)
7. Depth of a well: Metres (m)
8. Distance from classroom to school gate: Metres (m)
9. Distance from Srinagar to Jammu: Kilometres (km)
Q2 How many centimetres are there on a standard small school ruler?
Answer: A standard small school ruler has 15 centimetres (15 cm) marked on it.
Q3 Fill in the blanks with the correct number:
1. $1\text{ metre} = $ 100 centimetres.
2. $3\text{ metres} = $ 300 centimetres.
3. $500\text{ centimetres} = $ 5 metres.
4. $1\text{ kilometre} = $ 1000 metres.
5. Half a metre ($1/2\text{ m}$) = 50 centimetres.
Q4 Measurement Word Problem (The Tailor’s Tape):
A tailor bought 12 metres of cloth to stitch school uniforms. He used 8 metres 50 centimetres of cloth. How much cloth is left with him?
Step 1: Convert total cloth to cm: $12\text{ m} = 1200\text{ cm}$.
Step 2: Convert used cloth to cm: $8\text{ m } 50\text{ cm} = 850\text{ cm}$.
Step 3: Subtract: $1200 – 850 = 350\text{ cm}$.
Answer: 3 metres 50 centimetres of cloth is left.