A certain microprocessor requires 4.5 microseconds to respond to an interrupt. Assuming that the three interrupts $$ I_1, I_2$$ and $$I_3 $$ require the following execution time after the interrupt is recognized :
(i) $$ I_1 $$ requires 25 micro seconds
(ii) $$ I_2 $$ requires 35 microseconds
(iii) $$ I_3 $$ requires 20 microseconds
$$ I_1 $$ has the highest priority and $$ I_3 $$ has the lowest. What is the possible range of time for $$ I_3 $$ to be executed assuming that it may or may not occur simultaneously with other interrupts?