Bob wants to run a mile in the same time as his sister. If Bob’s time for a mile is currently 10 minutes and his sister’s time is currently 8 minutes 30 seconds, by what percent does Bob need to improve his time in order run a mile in the same time as his sister?
Choose the correct answer
A) 3% B) 15% C) 8% D) 10% E) 12%
Bob's time = 600 secs.   His sis' time = 510 secs.   Percent increase needed = (640-510/600) * 100 = 90/600 * 100= 
<gadget id="calculator">90/600 * 100</gadget>
<output>15</output>
15%. Ans (15%).
<result>B</result>
Bob wants to run a mile in the same time as his sister. If Bob’s time for a mile is currently 10 minutes and his sister’s time is currently 8 minutes 30 seconds, by what percent does Bob need to improve his time in order run a mile in the same time as his sister?