\frametitle{Example 4}
The approximate score interval for $p_f-p_m$ is then
$$0.1236-0.2645\pm$$
$$1.96
\sqrt{\frac{0.1236(1-0.1236)}{201.9208}+
\frac{0.2645(1-0.2645)}{101.9208}}$$
$$=(-0.2378,-0.0440)$$
(SAS code \href{http://users.wpi.edu/~jdp/ma2611d18/sas_code_ch5_5.txt}{here})
\vfill\hfill$\approx$