B = $\frac{1}{23.25}$ + $\frac{1}{25.27}$ +...+ $\frac{1}{73.75}$
2B = 2.($\frac{1}{23.25}$ + $\frac{1}{25.27}$ +...+ $\frac{1}{73.75}$)
2B = $\frac{2}{23.25}$ + $\frac{2}{25.27}$ +...+ $\frac{2}{73.75}$
2B = $\frac{25-23}{23.25} + $\frac{27-25}{25.27} +...+ $\frac{75-73}{73.75}
2B = $\frac{25}{23.25} - $\frac{23}{23.25}$ + $\frac{27}{23.25}$ - $\frac{25}{23.25}$ +...+ $\frac{73}{73.75}$ - $\frac{75}{73.75}$
2B = $\frac{1}{23}$ - $\frac{1}{25}$ + $\frac{1}{25}$ - $\frac{1}{27}$ +...+ $\frac{1}{73}$ - $\frac{1}{75}$
2B = $\frac{1}{23}$ - $\frac{1}{75}$
2B = $\frac{52}{1725}$
⇒ B =
$\frac{52}{1725}$ : 2
B =
$\frac{26}{1725}$
