1. Trying to predict weekty sales with a standard error of estimate of 51,955 , we would conchude that 68 percent at the pienichons would not be oft more than $1,955,95 percent would not be off by more $3,970, and 99,7 percent woeld not be off by more than $5,865 II. A confidence interval can be determined for the mean value of Y for a given value of X. Approximately 95 . of the values lie within two -standard errors of the regression line