In the accompanying diagram if   ${\mathrm{C}}_1=3\mathrm{\mu F}, C_2=6\mathrm{\mu F}, C_3=9\mathrm{\mu F}, C_4=12\mathrm{\mu F}, C_5=15\mathrm{\mu F}$ and ${\mathrm{C}}_6=18\mathrm{\mu F}$ , then the equivalent capacitance between the ends A and B is (in $\mathrm{\mu F}$) 

C₃ , C₅ and C₆ are in parallel.

$\mathrm{C}\text{'}=15+18+9=40 \mathrm{\mu F}$

C' and C₄ are in series.

$\mathrm{C}\text{'}\text{'}=\frac{\mathrm{C}\text{'}\times {\mathrm{C}}_4}{\mathrm{C}\text{'}+{\mathrm{C}}_4}=\frac{120}{13}\mathrm{\mu F}$

C₂ and C'' are in series.

$\mathrm{C}\text{'}\text{'}\text{'}=\mathrm{C}\text{'}\text{'}+{\mathrm{C}}_2=\frac{198}{13} \mathrm{\mu F}$

C₁ and C''' are in series.

  ${\mathrm{C}}_{\mathrm{eff}}=2.51$