Proportion Kya Hai? (:: Ka Matlab) | Class 8 Maths Book 1 Ch 7

πŸ“˜ Class 8 Β· Ganita Prakash Book 1Ch 7 Β· Proportional Reasoning-1Post 4 / 9⏱ 25–30 min
Proportion Kya Hai? (:: Ka Matlab) 🟰

βœ… Pehle Yeh Aata Hai?

Yeh post shuru karne se pehle, in teen sawaalon ko 1 minute mein khud try kijiye:

  1. 4 : 6 simplest?
  2. 10 : 15 simplest?
  3. Simplest form ka niyam (Post 3 β€” Ratio Ka Simplest Form)?
Answers dekho
  1. 2 : 3
  2. 2 : 3
  3. HCF 1 tak bhaag

Teeno sahi? Badhiya, aage chaliye! Koi galat hua? Koi baat nahi, Post 3 β€” Ratio Ka Simplest Form dekh lijiye.

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🎬 Kahani: Do Jug, Ek Swaad?

Mela mein do stall. Stall A: 4 glass paani mein 6 chammach sharbat. Stall B: 10 glass paani mein 15 chammach. πŸ₯€

Ravi: β€œB mein zyada sharbat, B meetha!” Neha: β€œPar B mein paani bhi zyada…”

Dono ka swaad same hai ya alag? Yahi sawaal hai proportion ka.

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πŸ“– Concept: Proportion = Do Ratio Barabar (a : b :: c : d)

πŸ’‘ Is post ki ek badi baat: Jab a : b aur c : d ek hi ratio family mein hon, kehte hain a : b :: c : d (β€œa is to b as c is to d”). Matlab: dono mein same rishta, chahe size alag.

Step 1: Tareeka 1: Dono simplify

4 : 6 = 2 : 3, 10 : 15 = 2 : 3 β†’ 4 : 6 :: 10 : 15. Swaad same! βœ…

WHY? Same simplest form = same family = same rishta. Kab aasaan: chhote numbers.

Step 2: Tareeka 2: Per glass (unit rate)

A: 6/4 = 1.5 chammach/glass. B: 15/10 = 1.5. Same! βœ…

Kab aasaan: jab β€œhar ek pe kitna” natural lage, ya kai options ki tulna (Post 5 β€” Ratio Se Tulna: Strong Ya Light?).

Step 3: Tareeka 3: Cross product

4 Γ— 15 = 60, 6 Γ— 10 = 60 β†’ barabar β†’ proportion βœ….

WHY kaam karta? 4/6 = 10/15. Dono taraf 6 Γ— 15 se guna: 4 Γ— 15 = 10 Γ— 6. Fraction hata diye, barabari bachi! Kab aasaan: bade/ajeeb numbers, ek missing term.

Step 4: Extremes aur means

a : b :: c : d mein a, d = extremes (bahar), b, c = means (andar). Niyam: extremes ka guna = means ka guna.

Step 5: Missing term

3 : 5 :: x : 40 β†’ 3 Γ— 40 = 5 Γ— x β†’ x = 24.

Doosra tareeka: 5 se 40 = Γ— 8, to 3 Γ— 8 = 24. Same factor wali soch! Check: 24 : 40 = 3 : 5 βœ…

πŸͺœ Atak Gaye? Aise Socho

  • Dono ratio alag likho.
  • Simplify karo, same?
  • Ya cross product: a Γ— d vs b Γ— c.
  • Missing term: factor dhoondo ya cross guna.
  • Check: naya ratio simplify karke dekho.

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πŸ” Deep Concept: Proportion Ka Asli Matlab: β€œEk Hi Factor Dono Pe”

4 : 6 se 10 : 15 tak: 4 Γ— 2.5 = 10, 6 Γ— 2.5 = 15. Dono terms ko same factor 2.5 mila. Yahi proportion hai!

Do nazariye, ek sach:

  • Andar ka factor: har ratio mein pehla = doosra Γ— 2/3 (dono mein same).
  • Beech ka factor: stall A se B tak har cheez Γ— 2.5.

Isliye missing term do tareeke se nikalta: β€œandar” (3 : 5 β†’ x = 40 Γ— 3/5) ya β€œbeech” (5 β†’ 40 = Γ— 8).

Galat proportion kaisa? Agar B mein 10 glass + 2 = 12? Nahi, paani 4 β†’ 10 hua (+6), sharbat 6 β†’ 15 (+9): jod same nahi, guna same. Yahi Post 1 β€” Proportional Badlaav Kya Hai? ka central idea: proportional = same factor, same farak nahi. 🎯

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✏️ Solved Examples

Example 1 (Easy): Kya 6 : 8 :: 15 : 20?

Cross: 6 Γ— 20 = 120, 8 Γ— 15 = 120 β†’ haan.

Check: dono = 3 : 4 βœ…

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Example 2 (Medium): Kya 5 : 7 :: 10 : 15?

5 Γ— 15 = 75, 7 Γ— 10 = 70 β†’ nahi.

Check: 10 : 14 hota tab haan βœ…

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Example 3 (NCERT style): 7 : x :: 21 : 36. x?

7 β†’ 21 = Γ— 3, to x Γ— 3 = 36 β†’ x = 12.

Check: 7 Γ— 36 = 252 = 12 Γ— 21 βœ…

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Mela ka faisla: 4 : 6 :: 10 : 15, swaad bilkul same. Ravi ne zyada sharbat dekha, par paani bhi utne hi guna zyada tha. πŸ₯€

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🏠 Proportion Roz Ki Zindagi Mein

  • πŸ₯€ Sharbat/chai: zyada log, same swaad.
  • πŸ—ΊοΈ Map: 1 cm : 5 km :: 7 cm : 35 km.
  • πŸ›’ Daam: 3 pen β‚Ή45 :: 5 pen β‚Ή75.
  • πŸ“· Photo enlarge: 4 : 6 :: 8 : 12, shakal same.
  • πŸ’Š Dawai: vajan ke proportion mein dose.

Photo ko 4 Γ— 6 se 8 Γ— 12 karo: proportion. 4 Γ— 6 se 6 Γ— 8 (dono + 2): chehra kheencha hua lagega!

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🧭 Kab Use Karein, Kab Nahi

SituationKya kareinKyun
Chhote numbersβœ… Simplify4 : 6, 10 : 15
Har ek pe kitnaβœ… Unit rate1.5/glass
Bade numbersβœ… Cross producta Γ— d = b Γ— c
Missing term, saaf factorβœ… Beech ka factorΓ— 8
Missing term, ajeeb factorβœ… Cross gunax = bc/a

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βŒβ†’βœ… Worked Mistake

Sawaal: Kya 2 : 3 :: 5 : 6? (β€œdono mein +3”)

❌ Galat: β€œ2 se 5 = +3, 3 se 6 = +3, to haan.”

βœ… Sahi: cross: 2 Γ— 6 = 12, 3 Γ— 5 = 15 β†’ nahi. Check: 2/3 β‰ˆ 0.67, 5/6 β‰ˆ 0.83 βœ…

🧠 Rule of thumb: Proportion mein guna ka factor same hona chahiye, jod nahi. Shak ho to cross product.

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πŸ“ 10 MCQs

Q1. 4 : 6 :: 10 : 15?

(a) Haan
(b) Nahi
(c) Pata nahi
(d) Sirf kabhi
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Sahi jawab: Dono 2 : 3 βœ…
  • (b) galat: Cross 60 = 60, isliye yeh galat.
  • (c) galat: Check karke pata chalta.
  • (d) galat: Hamesha same rahega, isliye yeh galat.

Q2. 3 : 5 :: x : 40, x?

(a) 24
(b) 38
(c) 15
(d) 25
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Bilkul sahi jawab: Γ— 8 βœ…
  • (b) galat: Jod wali galat soch, isliye yeh option sahi nahi.
  • (c) galat: 5 Γ— 3 galat jodi, isliye yeh option sahi nahi.
  • (d) galat: 40 Γ— 5/8 galat hai, isliye yeh option sahi nahi.

Q3. Extremes in a : b :: c : d?

(a) a, d
(b) b, c
(c) a, b
(d) c, d
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Sahi jawab: Bahar wale βœ…
  • (b) galat: Yeh means hain, isliye yeh galat.
  • (c) galat: Yeh pehla ratio hai, isliye yeh galat.
  • (d) galat: Yeh doosra ratio hai, isliye yeh galat.

Q4. 2 : 3 :: 5 : 6?

(a) Nahi
(b) Haan
(c) Dono +3 to haan
(d) Shayad
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Bilkul sahi jawab: 12 β‰  15 βœ…
  • (b) galat: Cross product alag hai.
  • (c) galat: Jod se proportion nahi.
  • (d) galat: Cross se pakka nahi, isliye yeh galat.

Q5. 6 : 8 :: 15 : ?

(a) 20
(b) 17
(c) 10
(d) 24
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Bilkul sahi jawab: Γ— 2.5 βœ…
  • (b) galat: Jod wali soch galat, isliye yeh option sahi nahi.
  • (c) galat: Ulta factor laga diya.
  • (d) galat: 6 : 8 β‰  15 : 24 hota, isliye yeh galat.

Q6. Cross product kyun?

(a) a/b = c/d ko bd se guna
(b) Yaad kiya niyam
(c) Jod se
(d) Kabhi nahi chalta
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Sahi jawab: Fraction hat jaate βœ…
  • (b) galat: Iska kaaran hai, ratta nahi.
  • (c) galat: Guna se aata, jod se nahi.
  • (d) galat: Hamesha chalta hai, isliye yeh galat.

Q7. Unit rate 6/4 aur 15/10?

(a) Dono 1.5
(b) 1.5 aur 2
(c) 2 aur 1.5
(d) 1 aur 1
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Bilkul sahi jawab: Same βœ…
  • (b) galat: 15/10 = 1.5 hai, isliye yeh galat.
  • (c) galat: 6/4 = 1.5 hai, isliye yeh galat.
  • (d) galat: Bhaag galat kiya, isliye yeh option sahi nahi.

Q8. 9 : x :: 3 : 7, x?

(a) 21
(b) 13
(c) 3
(d) 63
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Bilkul sahi jawab: Γ— 3 βœ…
  • (b) galat: Jod wali soch, isliye yeh galat.
  • (c) galat: Ulta factor laga, isliye yeh galat.
  • (d) galat: 9 Γ— 7 bina bhaag, isliye yeh galat.

Q9. Photo 4 Γ— 6 se 6 Γ— 8: shakal?

(a) Badlegi
(b) Same
(c) Double
(d) Proportion
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Sahi jawab: 4 : 6 β‰  6 : 8 βœ…
  • (b) galat: Ratio badal gaya, isliye yeh galat.
  • (c) galat: Double = 8 Γ— 12, isliye yeh galat.
  • (d) galat: Jod hai, guna nahi, isliye yeh galat.

Q10. Proportion ka central idea?

(a) Same factor
(b) Same farak
(c) Same jod
(d) Same unit
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Bilkul sahi jawab: Guna βœ…
  • (b) galat: Farak se nahi chalta, isliye yeh galat.
  • (c) galat: Jod se nahi chalta, isliye yeh galat.
  • (d) galat: Unit alag ho sakti, isliye yeh galat.

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❓ FAQs (Bachchon Ke Asli Sawaal)

1. :: aur = mein farak?

Same matlab; :: purana tareeka, = bhi chalta (a/b = c/d).

2. Kya ratio ka order proportion mein?

Haan, a : b :: c : d mein a-c aur b-d same cheezein.

3. Continued proportion?

a : b :: b : c, jaise 2 : 6 :: 6 : 18 (bΒ² = ac).

4. Kya 4 ratios?

Haan, a : b :: c : d :: e : f, sab same family.

5. Rate aur proportion?

Same rate = proportion: 60 km/h pe 2 h : 120 km :: 3 h : 180 km.

6. Aage?

Kaun sa strong? Post 5 β€” Ratio Se Tulna: Strong Ya Light?.

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πŸ‹οΈ Practice Zone (12 Sawaal)

Q1. Easy 5 : 8 :: 15 : 24?

Solution dekho

Haan. Check: 120 = 120 βœ…

Q2. Easy 3 : 4 :: 12 : 15?

Solution dekho

Nahi. Check: 45 β‰  48 βœ…

Q3. Easy 2 : 9 :: x : 45?

Solution dekho

10. Check βœ…

Q4. Easy Extremes, means: 1 : 2 :: 3 : 6?

Solution dekho

Extremes 1, 6; means 2, 3. Check: 6 = 6 βœ…

Q5. Medium x : 12 :: 15 : 36?

Solution dekho

5. Check: 5 Γ— 36 = 180 = 12 Γ— 15 βœ…

Q6. Medium 4 notebook β‚Ή100: 7 ka?

Solution dekho

β‚Ή175. Check: 4 : 100 :: 7 : 175 βœ…

Q7. Medium 1 cm : 4 km. 6.5 cm?

Solution dekho

26 km. Check βœ…

Q8. Medium 8 : 14 :: 20 : ?

Solution dekho

35. Check βœ…

Q9. NCERT style Continued proportion 4, 10, x?

Solution dekho

100 = 4x β†’ 25. Check: 4 : 10 :: 10 : 25 βœ…

Q10. NCERT style (x + 1) : 5 :: 6 : 10?

Solution dekho

x = 2. Check: 3 : 5 βœ…

Q11. NCERT style Kya 1.2 : 1.8 :: 4 : 6?

Solution dekho

Haan. Check: 7.2 = 7.2 βœ…

Q12. NCERT style Photo 5 Γ— 7 se chaudai 15 to lambai?

Solution dekho

21. Check βœ…

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🧠 HOTS (Sochne Wale Sawaal)

Q1. a : b :: c : d to (a + b) : b :: (c + d) : d?

Solution dekho

Haan: a/b + 1 = c/d + 1. Check: 4 : 6 β†’ 10 : 6 :: 25 : 15 βœ…

Q2. Kaunsa number har term mein jodo ki 5, 9, 1, 3 proportion bane?

Solution dekho

(5 + x)(3 + x) = (9 + x)(1 + x) β†’ 15 + 8x = 9 + 10x β†’ x = 3. Check: 8 : 12 :: 4 : 6 βœ…

Q3. a : b :: b : c, a = 3, c = 27. b?

Solution dekho

9. Check: 3 : 9 :: 9 : 27 βœ…

Q4. Kya 2 : 3 :: 3 : 2?

Solution dekho

Nahi: 4 β‰  9. Check βœ…

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πŸ† Olympiad Corner

Q1. 3 : x :: x : 12?

Solution dekho

6.

Q2. 2.5 : 4 :: 5 : x?

Solution dekho

8.

Q3. a : b = 3 : 4, a + b = 49?

Solution dekho

21, 28.

Q4. Fourth proportional of 4, 7, 12?

Solution dekho

21.

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πŸ’— CharuMam Motivation

Ab mela mein koi bhi stall ka swaad pehle hi bata doge! Proportion = same rishta, alag size. 🟰

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🟒 Master Recap

  • πŸ’‘ Chaabi: Jab a : b aur c : d ek hi ratio family mein hon, kehte hain a : b :: c : d (β€œa is to b as c is to d”). Matlab: dono mein same rishta, chahe size alag.
  • a : b :: c : d = same family.
  • Simplify, unit rate, ya cross product.
  • Extremes Γ— = means Γ—.
  • Cross product kyun: bd se guna.
  • Missing term: factor ya cross.
  • Guna same, jod nahi.

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