Page 158 - Bangladesh_classwiz_BOOK2018_rev_Neat

2
A‡bK mgq PjK mg~‡ni Mo ( ), = 0 Ges †f`v¼ (variance) , = 1 AvKv‡i web¨¯Í _v‡K bv|
2
mvaviYZ hw` ‡Kv‡bv PjK Gi Mo Ges †f`v¼ nq, Z‡e cwiewZ©Z Av`k© cwiwg‡Zv PjK n‡e-
−
=

ClassWiz K¨vjKz‡jU†i D³ cwiewZ©Z PjK w`‡q mivmwi m¤¢vebv wbY©q Kiv hvq|

aiv hvK, ‡Kv‡bv ¯‹z‡ji Qv·`i D”PZvi Mo 50 Bw Ges †f`v¼ 25 BwÂ| GLb Zv‡`i ga¨ n‡Z GKwU QvÎ evQvB
Kiv n‡jv| QvÎwUi D”PZv 43 Gi Kg nIqvi m¤¢vebv KZ n‡e?

2
GLb Av`k© cwiwg‡Zv PjK wbY©q Ki‡Z n‡e, = 43 Gi Rb¨ †hLv‡b, = 50 Ges = 25 ⇒ =
5 [cwiwg‡Zv e¨eavb (standard deviation)]

43 − 50
∴ = = −1.4
5

hv wb‡Pi wP‡Î †`Lv‡bv n‡jv,

CTR41(43p50)P5)=
Zvn‡j Avgiv ej‡Z cvwi, D³ ¯‹z‡ji cÖvq 8% Qv·`i D”PZv 43 BwÂi Kg n‡e|
Avevi Qv·`i D”PZv 42 Bw †_‡K 60 Bw nIqvi m¤¢vebv n‡e

= (42 ≤ ≤ 60 )
= ( 42−50 ≤ − ≤ 60−50 )
5 5
= (−1.6 ≤ ≤ 2)
= 0.922451 (K¨vjKz‡jUi n‡Z)
hv wb‡P †`Lv‡bv n‡jv

CTR412)pTR41p1.6)=

A_©vr, Qv·`i D”PZv 42 Bw †_‡K 60 Bw nIqvi m¤¢vebv 92% †_‡K †ewk|

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