Ted goes to work

[Brent@GMATPrepNow]

Ted always leaves his house at the same time to go to work. If he jogs at an average rate of 16 kilometers per hour, he arrives at work at 8:30 in the morning. If he jogs at an average rate of 8 kilometers per hour, he arrives at 9:15. At what speed must Ted jog to arrive at 9:00?
A) 8 2/3
B) 9 1/3
C) 9 3/5
D) 10 1/3
E) 11 1/5

[cramya]

Is it C) 9 3/5

[cramya]

let x be the distance

x = 16t

x= 8 *(4t+3) /4

t = 3/4

x=12

let v the speed to needed to reach at 9

v * (3/4+1/2) = 12

v = 9 3/5

[logitech]

x/8 - x/16 = 3/4 (45 min )

X=12

12/16 = 3/4 (45 mins) , so he leaves home at 7:45

to be at work at 9:00 ( 5/4 hrs)

12 = 5/4 x V

V = 48/5

[Brent@GMATPrepNow]

Nice - the answer is C