Class 8 Maths Part 2 Chapter 5: Tales by Dots and Lines (Hinglish Notes)
Ye chapter 5 lines mein
Tales by Dots and Lines data ko do tarah se dekhta hai. Dot plot se ye dikhaata hai ki mean dono taraf ki kul doori ko santulit karta hai, aur value jodne, hataane ya badalne par mean aur median kaise badalte hain. Line graph, infographic aur activity strip se ye sikhaata hai ki data ko kadam-dar-kadam kaise padhein aur soch-samajhkar nateeje nikaalein.
Ye chapter kis baare mein hai?
Pichhle saal mean ek ‘barabar hissa’ tha aur median beech ki value. Ye chapter dono ko dot plot se phir dekhta hai aur poochhta hai ki data badalne par ye kaise badalte hain, phir line graph, infographic aur activity strip ki taraf badhta hai, taaki dekhein ki asli data humein kya bata sakta hai aur kya nahi.
Mean ek santulan bindu
Do sankhyaon ka mean theek unke beech mein hota hai. Zyada sankhyaon mein mean hamesha sabse chhoti aur sabse badi value ka beech nahi hota; balki mean se neeche ki values tak ki kul doori upar ki values tak ki kul doori ke barabar hoti hai. 2, 4 aur 9 ka mean 5 hai: baayin taraf dooriyaan 3 + 1 = 4 aur daayin taraf 4. Aisa santulan sirf ek bindu par hota hai. Padhein: mean (ausat) kya hai?.
Jab data badalta hai
Mean se badi value jodne par mean badhta hai, chhoti value se ghatta hai, aur barabar value se kuch nahi badalta; value hataane par ulta hota hai. Kai values bhi bina mean hilaaye jodi ja sakti hain agar unki dooriyaan santulit hon. Har value 10 badhe to mean 10 badhta hai; har value do guni ho to mean do guna hota hai, jo algebra se saabit hota hai.
Median aur frequency table
Median se badi value jodne par median sirf badh sakta hai ya waisa hi reh sakta hai; chhoti value use sirf ghata sakti hai ya waisa hi chhod sakti hai. Jab data frequency table mein ho, to mean ke liye har value ko uski frequency se guna karein, aur median ke liye running total se beech ke sthaan tak pahunchein. 36 vidyaarthiyon ke parivaar ke size ka mean lagbhag 5.22 aur median 5 hai. Padhein: frequency table se mean aur median.
Anjaani values nikaalna
Kyonki jod = mean × values ki sankhya, mean se chhooti hui value nikaali ja sakti hai: 39.2 kg ausat wale das pehalwaanon ka kul vazan 392 kg hai, to mita hua vazan 392 − 349 = 43 kg hai. Galat entry bhi isi tarah theek hoti hai.
Spreadsheet
Spreadsheet cells ki ek digital copy hai jinke naam column aur row se bante hain, to E5 matlab column E, row 5. =SUM(B3:G3) jaisa formula ek row jodta hai aur =AVERAGE(G2:G23) ek column ka ausat deta hai, isliye teacher poori class ke marks ka total aur ausat seconds mein nikaal sakte hain.
Line graph
Line graph data ke bindu rekhaon se jodta hai aur samay ke data ke liye theek hai. Ise do kadam mein padhein: pehle pehchaanein ki kya diya hai (sheershak, aksh, scale, rang aur pattern), phir nishkarsh nikaalein aur vyaakhya karein. Punjab ka mahine ka adhiktam taapmaan lagbhag 19°C se 38°C tak jhoolta hai, jabki Kerala ka lagbhag 29°C aur 33°C ke beech rehta hai. Padhein: line graph kaise padhein?.
Infographic aur activity strip
Infographic data ko chitra mein samet deta hai: ek naksha dikhaata hai ki ek rekha ke dakshin aur poorab ke rajya chaawal pasand karte hain aur uttar-paschim ke gehun. 48 aadhe-aadhe ghante ke boxon wali activity strip dikhaati hai ki din kaise beeta, aur strips ki tulna se school ke din, chhutti aur ghoomne-firne ka pata chalta hai.
Aage badhne se pehle
Mean dooriyon ko santulit karta hai aur median beech mein rehta hai, aur data badalne par dono anumaan laayak dhang se badalte hain. Line graph samay ke saath badlaav dikhaate hain, aur data dekhne se naye sawaal uthte hain. Har sawaal ka jawaab Part 2 Chapter 5 ke NCERT solutions mein hai.
Key terms (zaroori shabd)
| Term | Matlab |
|---|---|
| Mean (ausat) | Sab values ka jod, values ki sankhya se bhaag; wo bindu jahaan dono taraf ki dooriyaan santulit hoti hain. |
| Median (maadhyika) | Kram mein lagaaye data ki beech wali value; values sam sankhya mein hon to beech ki do values ka ausat. |
| Dot plot | Number line jismein har value ke liye ek bindu hota hai, aur dohraayi value ke bindu ek ke upar ek lagte hain. |
| Kendriya pravritti ka maap | Ek akeli value, jaise mean ya median, jo data ke kendra ko dikhaati hai. |
| Frequency (baarambaarta) | Koi value data mein kitni baar aati hai. |
| Frequency table | Table jismein har value uski frequency ke saath likhi hoti hai. |
| Running total | Frequencies ko ek ke baad ek jodna, jisse pata chale ki kisi sthaan par kaun si value hai. |
| Spreadsheet | Cells ki digital table, jinke naam column ke akshar aur row ki sankhya se bante hain, jaise E5. |
| Formula | Cell mein likha nirdesh, jaise =SUM(B3:G3) ya =AVERAGE(G2:G23), jo doosre cells se hisaab lagaata hai. |
| Line graph | Graph jismein data ke bindu rekhaon se jude hote hain; zyaadatar samay ke saath badlaav dikhaane ke liye. |
| Clustered column graph | Bar graph jismein columns ke samooh agal-bagal hote hain, har category ka ek samooh. |
| Infographic | Data, rang aur chhote text ko milaakar ek nazar mein kahaani batane wala chitra. |
| Activity strip | Tay samay wale boxon ki patti, jismein rang bharkar dikhaaya jaata hai ki us samay kya kiya. |
Is chapter ke topics
Practice karo
-
2, 4 aur 9 ka mean hai:
Jawab dekho
Jawab: (b) 5
-
Data ki har value mein 10 jodne par mean:
Jawab dekho
Jawab: (b) 10 badh jaata hai
-
4, 6, 8, 11, 13 ka median hai:
Jawab dekho
Jawab: (b) 8
-
Spreadsheet mein cell E5 kahaan hai?
Jawab dekho
Jawab: (b) column E, row 5
-
Line graph mukhya roop se kya dikhaate hain?
Jawab dekho
Jawab: (b) samay ke saath badlaav
-
10 values ka mean 39.2 hai. Unka jod hai:
Jawab dekho
Jawab: (c) 392
Students ke sawal
Class 8 Maths Part 2 Chapter 5 ke mukhya topic kya hain?
Mean ek santulan bindu ke roop mein; value jodne, hataane ya sab ko ek jaisa badalne par mean kaise badalta hai; median kaise badalta hai; chhooti value nikaalna; frequency table se mean aur median; spreadsheet; line graph; infographic; aur activity strip.
Kya Tales by Dots and Lines naye NCERT Class 8 Maths book mein hai?
Haan. Ye Ganita Prakash, Grade 8 Part 2 ka Chapter 5 hai, pehle edition (December 2025) mein pages 103 se 134 tak.
Mean ko santulan bindu kyon kehte hain?
Kyonki mean se neeche ki values tak ki kul doori hamesha upar ki values tak ki kul doori ke barabar hoti hai, jaise us bindu par tika hua see-saw. Koi aur bindu aisa nahi karta.
Line graph kab istemaal karein?
Jab data samay ke saath badalta hai, jaise mahine ka taapmaan ya saal ke launch. Bindu jodne se badhna, ghatna aur pattern saaf dikhte hain, aur bahut saare bindu bhi padhne mein aasaan rehte hain, jahaan column graph bhara-bhara lagta.
Koi sawal atak gaya?
Photo lo, Lagnever AI step-by-step samjhayega. 7 din ka trial sirf ₹2.
Google Play se app lo Browser mein kholo
Parents ke liye: trial ke baad plan har mahine UPI ya card autopay se renew hota hai. App mein kabhi bhi cancel kar sakte hain.