Question
The mean of five observations is 4 and their variance is 5.2. If three of these observations are 1,2 and 6 , then the other two are
BITSAT
Mathematics
Statistics
2022
BITSAT 2022
BITSAT Mathematics Question (2022) — Solution
Options
- A. 2 and 9
- B. 3 and 8
- C. 4 and 7
- D. 5 and 6
Answer
C. 4 and 7
Step-by-step solution
Let the two unknown items be x and y. Then, Mean =4 1+2+6+x+y 5 =4 x+y=11 (i) and variance =5.2 1^2+2^2+6^2+x^2+y^2 5 -( mean )^2=5.2 41+x^2+y^2=5(5.2+16) array ll & 41+x^2+y^2=106 \\ & x^2+y^2=65 array On solving Eqs. (i) and (ii), we get x=4, y=7 or x=7, y=4
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