Jenny can jog twice as fast as she can walk. She was able to jog the first 12 miles to her grandmother house but then she tried and walked the remaining 3 miles. If the total trip took 2 hours then what was her average jogging speed

Solution

J e nn y c an j o g tw i ce a s f a s t a s s h e c an w a l k . S h e w a s ab l e t o j o g t h e f i rs t 12 mi l es t o h er g r an d m o t h er h o u se b u t t h e n s h e t r i e d an d w a l k e d t h e re mainin g 3 mi l es . I f t h e t o t a l t r i p t oo k 2 h o u rs t h e n w ha t w a s h er a v er a g e j o gg in g s p ee d

joging speed : 9

Solution steps

Translate the problem into an equation:

\frac{12}{x} + \frac{3 \cdot 2}{x} = 2

Solve for

x, \frac{12}{x} + \frac{3 \cdot 2}{x} = 2 : x = 9

joging speed : 9