SOLUTION: Helped by a strong jet stream, a LA to Boston plane flew 10%faster than usual and made the 4400KM trip in 30 min less time than usual. At what speed does the plane usually fly?

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Question 195402This question is from textbook
: Helped by a strong jet stream, a LA to Boston plane flew 10%faster than usual and made the 4400KM trip in 30 min less time than usual. At what speed does the plane usually fly? This question is from textbook

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Helped by a strong jet stream, a LA to Boston plane flew 10%faster than usual
and made the 4400KM trip in 30 min less time than usual.
At what speed does the plane usually fly?
:
Let s = usual speed of the jet
then
1.1s = the faster speed
:
Change 30 min to hrs; 1%2F2 hrs
:
Write a time equation: Time = dist%2Fspeed
:
faster time + .5 hr = usual time
4400%2F%281.1s%29 + 1%2F2 = 4400%2Fs
get rid of those annoying denominators, multiply equation by 110s:
110s*4400%2F%281.1s%29 + 110s*1%2F2 = 110s*4400%2Fs
cancel out the denominators, results
100(4400) + 55s = 110(4400)
:
440000 + 55s = 484000
:
55s = 484000 - 440000
:
55s = 44000
s = 44000%2F55
s = 800 mph is the usual speed
;
:
Check solution by finding the times:
4400/800 = 5.5 hrs
4400/(1.1*800) = 5 hrs; confirms our solution