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Difference between revisions of "1997 PMWC Problems/Problem I13"
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== See also ==
 
{{PMWC box|year=1997|num-b=I12|num-a=I14}}
 
{{PMWC box|year=1997|num-b=I12|num-a=I14}}
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[[Category:Introductory Algebra Problems]]

Revision as of 12:14, 15 January 2008

Problem

A truck moved from A to B at a speed of 50 km/h and returns from B to A at 70 km/h. It traveled 3 rounds within 18 hours. What is the distance between A and B?

Solution

The truck moved from A to B back and forth once in 18/3=6 hours. Let the time that it takes to go from A to B be $T_1$, and let the time it takes to go from B to A be $T_2$.

$T_1+T_2=6$

$50T_1=70T_2\Rightarrow T_1=\frac{7}{5}T_2$

$\frac{12}{5}T_2=6\Rightarrow T_2=\frac{5}{2}$

Therefore the distance from A to B is $\frac{5}{2}*70=\boxed{175}$.

See also

1997 PMWC (Problems)
Preceded by
Problem I12 		Followed by
Problem I14
I: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15
T: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10
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