Time, Distance, Speed Problems

[razakazmii]

Following is the question:

In a flight of 600km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200km/hr and the time of flight increased by 30 minutes. The duration of the flight is?

I googled this problem, but could not find the satisfactory solution of this question.

 

[MarkFL]

When the weather isn't bad, we may write (where distances are in km and time is in hours):

[MATH]d=vt[/MATH]
When the weather is bad, we have:

[MATH]d=(v-200)\left(t+\frac{1}{2}\right)[/MATH]
We now have two equations in two unknowns. Can you proceed?

 

[razakazmii]

When the weather isn't bad, we may write (where distances are in km and time is in hours):

[MATH]d=vt[/MATH]
When the weather is bad, we have:

[MATH]d=(v-200)\left(t+\frac{1}{2}\right)[/MATH]
We now have two equations in two unknowns. Can you proceed?

I would really be grateful to you if you proceed this question.

 

[Steven G]

You want time,t, so get rid of r. You have d=rt, so r=??. Now substitute this new way of writing r into the 2nd equation. Then this equation will have only t, so try to solve for t. If you have trouble, then post back with your work.