Question 446153
dep 6th May 1200
Arr 18th may 7.00 

Time = 11 days + 19 hours = 283 hours
scheduled speed = 13.5 kts 
distance = 3822 miles

..
13th May 0100 hours time elapsed =6 days and 13 hours = 157 hours
To reach on schedule it has 283-157 = 126 hours

Let it travel x kts at 14.4 kts/h
time = x/14.4
Balance at 10 kts/h
Time at 10 kts/hr =(1554-x)/10 

x/14.4 + (1554-x)/10= 126
10x+14.4(1554-x)= 10*14.4*126
10x+22,377.6 -14.4x =18144
-4.4x=-4233.6
x=962.18 kts.
At 14.4 kts/hr it will take 962.18/14.4 ---hours
=66.81 hours ===> 2 days 18 hours 48 minutes
16th may 1948 hours it has to reduce to 10 kts/hr to be on schedule.