Question 145769


Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r (Note: these are givens--basic definitions. You don't need to figure these out but they should make sense)

Let t=time it takes the plane flying from base to intercept the first acft. 

Now we know that when the distance the first plane flies plus the distance the second plane flies equals 200 km, the second plane will have intercepted the first plane. (In other words, they will be together.)

Distance first plane flies=350t (r*t)
Distance second plane flies=450t
So, our equation to solve is:
350t+450t=200 or
800t=200  divide both sides by 800
t=1/4 hr------------------------------answer

CK
In 1/4 hr, first plane travels 350*(1/4)=87.5 km
In 1/4 hr, second plane travels 450*(1/4)=112.5 km
87.5+112.5=200
200=200


Also, we know that the planes are approaching each other at the rate of 350+450 km/hr
Hope this helps---ptaylor