. The mean of certain number of observations is 46. If four observation whose mean is 52 are removed, the mean becomes 44.5. The original number of obse

Best Answer

Answer ||| B Solution ||| Let the number of observations be ‘n’. So, sum of ‘n’ observations = 46 × n Sum of 4 numbers being removed = 52 × 4 = 208 So, now sum of (n – 4) observations = 44.5 × (n – 4) ⇒ Sum of (n – 4) observations = Sum of n observations – Sum of 4 numbers ⇒ 44.5 × (n – 4) = 46 × n – 208 ⇒ 44.5 × n – 178 = 46 × n – 208 ⇒ 1.5n = 208 – 178 = 30 ⇒ n = 20 So, the answer is 20 observations (option B).