Statistics

For a statistical data x1, x2, , x10 of 10 values, a student obtained the mean as 5.5 and i=110xi2=371. He later found that he had noted two values in the data incorrectly as 4 and 5, instead of the correct values 6 and 8, respectively. The variance of the corrected data is

1. 5
2. 7
3. 9
4. 4

Answer

(2) 7

Solution

Only the sums change: x=55-(4+5)+(6+8)=60 mean =6

x2=371-(16+25)+(36+64)=430

2= 43010-62=7

Answer: (2)