Q13:c／ｅ
Is the number of seconds required to travel d1 feet at r1 feet per second greater than the number of seconds required to travel d2 feet at r2 feet per second?
(1) d1 is 30 greater than d2.
(2) r1 is 30 greater than r2.
I think C is right. Is d1/r1 greater than
d2/r2?
d1/r1-d2/r2=(d1*r2-d2*r1)/(r1*r2)
if together with term 1 and 2,
d1=1.3d2 and r1=1.3r2 ,
so (d1*r2-d2*r1)/(r1*r2)=(1.3d2*r2-d2*1.3r2)/(r1*r2)=0
therefore, the time is the same.
in other words, it suffiently answer the question.
Am I right? | 
