Every day, Tom walks from his home to his office, via the same route,

Question

Every day, Tom walks from his home to his office, via the same route, covering s feet at a speed of x feet per minute. Today he took a different route and ended up walking 10% more than he usually does, at a speed of x meters per minute. What is the percentage change in the time he took today compared to the time he takes on a usual day? (1 feet = 0.3 meter)

A. 10% decrease

B. 10% increase

C. 67% decrease

D. 67% increase

E. 200% decrease

A. 10% decrease

B. 10% increase

C. 67% decrease

D. 67% increase

E. 200% decrease

chetan2u · Accepted Answer

(I) Substitute values for variables..
Let s = 100 and x=10..
Time taken while going 100 at 10 feet per minute=  \frac{100}{10}=10  minutes
Time taken on return 1.1*100 at 10 meter per minute or @ \frac{10}{0.3}  feet per minute=  110/\frac{10}{0.3}=\frac{33}{10}=3.3  minutes

Change or decrease =  \frac{10-3.3}{10}*100=67 %

(II) Algebra..
Time taken while going s feet at x feet per minute=  \frac{s}{x}  minutes
Time taken on return 1.1*s at x meter per minute or @ \frac{x}{0.3}  feet per minute=  1.1s/\frac{x}{0.3}=\frac{0.33s}{x}  minutes

Change or decrease =  (\frac{s}{x}-\frac{0.33s}{x})/\frac{s}{x}*100=(1-0.33)*100=67 %

C

Archit3110 · Answer

let distance s feet = 10feet = 3 mtr
speed = 10 feet per minute ; total time ; 3/10 ; .3 min
new distance ; 3*1.1 ; 3.3 mtrs 
speed ; 10/.3 feet per min; time taken ; 3.3/33.33 = .099 min
% ∆ in time = .099-.3/.3 ; (67%)

IMO C

Tigi75 · Answer

"Tom ended up walking 10% more" could refer to time or distance, as it is new route...

CrackverbalGMAT · Answer

It says   walking   10% more  than he usually does , and hence it refers to distance.

If it was,   taking   10% more than he usually does, then would have referred to time. (In which case the answer would simply have been 10% increase)

Hope this helps

Arun Kumar

JeffTargetTestPrep · Answer

Old route:

time = distance/rate

time = d/x

New route:

distance = 1.1d

We have to be careful to express the speed in the same unit of measurement:

rate = x m/min = (x m/1 min)(1 ft/0.3 m) = x/0.3 ft/min

time = 1.1d/(x/0.3) = (0.33)(d/x)

new time = (0.33)(old time)

A factor of 0.33 corresponds to a 67% decrease.

Answer: C

Goldenfuture · Answer

Distance  
  Speed  
 Time 
  Final Cal

x ft - 1 min

0.3x m in 1 min

Old 
 Let s = 18 
 18xm in 60 min 
 s/18 
 1 hour

New 
 1.1s 
 60x m 
 1.1/60 
 1.1*18/60 
 0.33 
 ~67% decrease

1/18 to 1.1/60

Dream009 · Answer

Ratio of speed changes from .3 to 1 - so even if distance remained same ratio of time would be flip from 10 to 3 ~approx 70% decline - from the options only C makes sense.

Every day, Tom walks from his home to his office, via the same route,

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	Distance	Speed	Time	Final Cal
		x ft - 1 min
		0.3x m in 1 min
Old	Let s = 18	18xm in 60 min	s/18	1 hour
New	1.1s	60x m	1.1/60	1.1*18/60	0.33	~67% decrease

			1/18 to 1.1/60

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Every day, Tom walks from his home to his office, via the same route,

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