The marks of some students were listed out of $ 75 $. The SD of marks was found to be $ 9 $. Subsequently the marks were raised to a maximum of $ 100 $ and variance of new marks was calculated. The new variance is,

Question

The marks of some students were listed out of $ 75 $. The SD of marks was found to be $ 9 $. Subsequently the marks were raised to a maximum of $ 100 $ and variance of new marks was calculated. The new variance is,, $ 144 $, $ 122 $, $ 81 $, None of these

MARKS App · Accepted Answer

Given, σ = 9 Let a student obtains x out of 75 . Then his marks out of 100 are 4 x 3 . ⇒ Each observation is multiplied by 4 3 ⇒ New σ = 4 3 × 9 = 1 2 , ⇒ New Variance = σ 2 = 1 4 4

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