Time distance question... Please help

Brent@GMATPrepNow wrote:

Mary.006 wrote:A truck travels 20 miles due north', 30 miles due east , and then 20 miles due north. How many miles is the truck from the starting point.?

20.3
70
44.7
50

Altogether, the truck drove 40 miles north and 30 miles east.
So, 30 and 40 represent the two LEGS of a right triangle.
The truck's distance from the starting point (i.e., the hypotenuse) can be found using the Pythagorean Theorem.
30² + 40² = hypotenuse²
900 + 1600 = hypotenuse²
2500 = hypotenuse²
So, hypotenuse = 50
Answer: D


ALTERNATIVELY, we might recognize that this right triangle is an ENLARGED version of a 3-4-5 right triangle. This new right triangle is 10 TIMES as big as the 3-4-5 right triangle. So, the lengths are 30-40-50, meaning that the hypotenuse has length 50

Cheers,
Brent

Mary.006 wrote:A truck travels 20 miles due north', 30 miles due east , and then 20 miles due north. How many miles is the truck from the starting point.?

20.3
70
44.7
50