Question 1014720
aeroplane left 30min. later than its scheduled time and in order to reach distination 1500km away in time, it has to increase its speed by 250km/hr from its usual speed. determine its usual speed.
<pre>Let usual speed be S
Then time it usually takes is: {{{matrix(1,1,"1,500"/S)}}}
After increasing its speed, new speed becomes: S + 250
Time taken at increased speed: {{{matrix(1,1,"1,500")/(S + 250))}}}
We now get: {{{matrix(1,1,"1,500")/S = matrix(1,1,"1,500")/(S + 250) + 30/60}}}
Solve for S, or regular speed to get: {{{highlight(highlight_green(highlight(750)))}}} km/h