Solution:
Number of failures from different cities:
$$\eqalign{
& \text{A}→ 1.25\times100000\times\frac{3}{10} \cr
& \,\,\,\,\,\, = 37500 \cr
& \text{B}→ 3.14\times100000\times\frac{3}{8} \cr
& \,\,\,\,\,\, = \frac{314000\times3}{8} \cr
& \,\,\,\,\,\, = 117750 \cr
& \text{C}→ 1.08\times100000\times\frac{5}{9} \cr
& \,\,\,\,\,\, = 108000\times\frac{5}{9} \cr
& \,\,\,\,\,\, = 60000 \cr
& \text{D}→ 2.27\times100000\times\frac{3}{4} \cr
& \,\,\,\,\,\, = 227000\times\frac{3}{4} \cr
& \,\,\,\,\,\, = 170250 \cr
& \text{E}→ 1.85\times100000\times\frac{2}{5}\cr
& \,\,\,\,\,\, = 185000\times\frac{2}{5} \cr
& \,\,\,\,\,\, = 74000 \cr
& \text{F}→ 2.73\times100000\times\frac{5}{12} \cr
& \,\,\,\,\,\, = 273000\times\frac{5}{12} \cr
& \,\,\,\,\,\, = 113750 \cr } $$
So,
The maximum number failures are from city D.
