Let's assume the initial speed of the flight is F. And the time taken is t.
Given the distance to be travelled, 11200.
We know distance = speed *time.
So, 11200=Ft-->1
Due to bad weather, the flight started with a three-hour delay. Given that the flight speed increased by 100kmph, the delay would be reduced to one hour. So, it is nothing but the travel time is reduced by 2 hours.
In that case, the equation will become 11200=(F+100)*(t-2)-->2
Equation 1 can be re-written as t=$\frac{11200}{F}$-->3
Now Equation 2: $\frac{11200}{F+100}$=t-2
$\Rightarrow$ = $\frac{11200}{F+100}$+2=t
$\frac{11200+2\left(F+100\right)}{F+100}=t$
$t=\frac{11400+2F}{F+100}$-->4
Divide equation 3 by equation 4:'
$\frac{t}{t}=\frac{\frac{11200}{F}}{\frac{11400+2F}{F+100}}$
$\Rightarrow$ $\frac{\left(11400+2F\right)}{F+100}=\frac{11200}{F}$
$\left(11400+2F\right)\cdot F=\left(F+100\right)\cdot11200$
$\left(11400F+2F^2\right)=\left(11200F+1120000\right)$
$\ 2F^2+200F-1120000=0\ \Rightarrow\ F^2+100F-560000=0$
So, F=700 or -800. Speed can't be negative. So, the speed is 700km/hr.
Now, if the speed is increased by 350, the new speed will be 1050.
Hence, the time taken will be $\frac{11200}{1050}=\frac{32}{3}=10\ \frac{2}{3\ }hrs=10hrs\ 40\min$
The flight has to start at 6:30 am, but it is delayed by 3 hrs. So, the actual time is 9:30 am.
10hrs: 40mins from that will be 8:10 pm