SOS

5nCr2(.5)^2(.5)^3

$\begin{array}{rcl} 5Cr2(0.5)^2(0.5)^3 \\ &=& \binom{5}{2}\cdot 0.5^2\cdot 0.5^3\\ &=& \binom{5}{2}\cdot 0.5^{2+3}\\ &=& \binom{5}{2}\cdot 0.5^{5}\\ &=& \frac{5}{2}\cdot\frac{4}{1}\cdot 0.5^{5}\\ &=& \frac{5}{2}\cdot\frac{4}{1}\cdot 0.03125\\ &=& 10\cdot 0.03125\\ &=& 0.3125\\ \mathbf{5Cr2(0.5)^2(0.5)^3 }& \mathbf{=} & \mathbf{0.3125}\\ \end{array}$