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If the mean and variance of the data 65,68,58,44,48,45,60, , ,60 where > , are 56 and 66.2 respectively, then 2+ 2 is equal to .
6344
Sum of the 8 known values =448 ⇒ + =10 56-448=112
2= xi210- x2 xi2=10(66.2+3136)=32022
Squares of known values: 4225+4624+3364+1936+2304+2025+3600+3600=25678
∴ 2+ 2=32022-25678=6344
Answer: 6344
If the mean and variance of five observations are 245 and 19425 respectively and the mean of the first four observations is 72, then the variance of the first four observations is equal to
Let a1, a2, a10 be 10 observations such that k=110 ak=50 and k<j ak aj=1100. Then the standard deviation of a1, a2, , a10 is equal to :
The mean and standard deviation of 15 observations were found to be 12 and 3 respectively. On rechecking it was found that an observation was read as 10 in place of 12 . If and 2 denote the mean and variance of the correct observations respectively, then 15 ( + 2+ 2 ) is equal to .