Bob wants to run a mile in the same time as his sister. If Bob’s time for a mile is currently 10 minutes 40 seconds and his sister’s time is currently 9 minutes 17 seconds, by what percent does Bob need to improve his time in order run a mile in the same time as his sister?  Select.
A) 3 %
B) 5 %
C) 8 %
D) 10 %
E) 13 %

Rationale: bob ' s time = 640 secs . his sis ' time = 557 secs . percent increase needed = ( 640 - 557 / 640 ) * 100 = 83 / 640 * 100 = 13 % . ans ( e ) .
Answer: E