(1 point) Two random samples are selected from two independent populations. A summary of the samples sizes and sample means is given below: $$ \begin{array}{ll} n_{1}=35, & \bar{x}_{1}=51 \\ n_{2}=38, & \bar{x}_{2}=74.4 \end{array} $$ If the $97 \%$ confidence interval for the difference $\mu_{1}-\mu_{2}$ of the means is $(-27.8519,-18.9481)$, what is the value of the pooled variance estimator? (You may assume equal population variances.) Pooled Variance Estimator = SP.JG.323