In: Math
Your scores from an afternoon of bowling were 128, 189, 156, 143, 117, and 152. Your sisters bowling scores were 204, 176, 189, 198, 218, 177, 190,and 203. Find the(two-sided) 98% confidence interval for (sigma^2*you) /(sigma^2*Sister). Assume bowling is normally distributed.
| Your scores bowling ( X ) | Σ ( Xi- X̅ )2 | sisters bowling ( Y ) | Σ ( Yi- Y̅ )2 | |
| 128 | 380.25 | 204 | 92.6406 | |
| 189 | 1722.25 | 176 | 337.6406 | |
| 156 | 72.25 | 189 | 28.8906 | |
| 143 | 20.25 | 198 | 13.1406 | |
| 117 | 930.25 | 218 | 558.1406 | |
| 152 | 20.25 | 177 | 301.8906 | |
| 190 | 19.1406 | |||
| 203 | 74.3906 | |||
| Total | 885 | 3145.5 | 1555 | 1425.8748 |
Mean X̅ = Σ Xi / n
X̅ = 885 / 6 = 147.5
Sample Standard deviation SX = √ ( (Xi - X̅ )2 / n - 1
)
SX = √ ( 3145.5 / 6 -1 ) = 25.0819
Mean Y̅ = ΣYi / n
Y̅ = 1555 / 8 = 194.375
Sample Standard deviation SY = √ ( (Yi - Y̅ )2 / n - 1
)
SY = √ ( 1425.8748 / 8 -1) = 14.2722
Confidence Interval

F(0.02/2, n1,n2) = F(0.02/2, 5,7) =
7.46
F(0.02/2, n1,n2) = F(0.02/2, 7,5) =
10.46
Lower Limit = ( 629.1017 / 203.6957 ) * ( 1 / F(0.02/2, 5,7)) =
0.4140
Upper Limit = ( 629.1017 / 203.6957 ) * ( F(0.02/2, 7,5)) =
32.3051
98% Confidence interval is ( 0.414 , 32.3051
)
( 0.4140 <
< 32.3051 )