iamsiddharthkapoor
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
(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