Question 764178
A boat completed one quarter of it's journey at 9:30 and two thirds
 at 10:50. 
Assuming a constant speed what time did it start and finish?
:
Let the total journey = 1
Find the portion of the journey covered between 9:30 and 10;50
{{{2/3}}} - {{{1/4}}} = {{{8/12}}} - {{{3/12}}} = {{{5/12}}} of the journey
Find the no. of minutes between 9:30 and 10:50 = 80 minutes
:
Distance varies directly with time, use a ratio equation
Let t = total time for the journey
{{{(5/12)/1}}} = {{{80/t}}}
Cross multiply 
{{{5/12}}}t = 80 * 1
t = 80*{{{12/5}}}
t = 192 minutes for the whole journey
:
Start time to 9:30; {{{1/4}}} * 192 = 48 minutes
Start time = 9:30 - 48 min = 8:42 is the start time
:
Find the completion time
8:42 + 192 min = 8:42 + 3:12 = 11:54 is the completion time