Easy math problem winner gets 10 pts! :D?

Question

Shawna liked to jog late at night. One night she noticed an unusual phenomenon: as she jogged, dogs would hear her and bark. After the first dog had barked for about 15 seconds, two other dogs would join in and bark. And then in about another 15 seconds, it seemed that each barking dog would "inspire" two more dogs to start barking. Of course, long after Shawna passed the first dog, it continued to bark, as dogs are inclined to do. After about 3 minutes, how many dogs were barking (as a result of Shawna passing the first dog)?

Answer 1

Two possibilities -

If each dog "inspired" two dogs ONCE, then didn't inspire any others, the answer is: 8,191 broken down as follows:

0 sec=1

15 sec = 2 more

30 sec = 4 more

45 sec = 8 more

1 minute = 16 more

1 m in 15 sec = 32 more

1 min 30 sec = 64 more

1 min 45 sec = 128 more

2 minutes = 256 more

2 min 15 sec = 512 more

2 min 30 sec = 1024 more

2 min 45 sec = 2048 more

3 minutes = 4096 more

Added together, 8,191 dogs barking

If each dog inspires 2 dogs FOR each 15 seconds he's been barking,  the above breakdown (Dodger) is correct, BUT the equation starts when the first dog barks (0 secs), so we need one more step, which means at 3 minutes FROM the first dog barking, the number would be:  531,441 dogs

Answer 2

about 3 minutes? not exactly 3 minutes? not sure in that case

Answer 3

177,147 or 3^11

Here's the dogs per 15 second increment:

15 sec = 1

30 sec = 3

45 sec = 9

1 minute = 27

1 m in 15 sec = 81

1 min 30 sec = 243

1 min 45 sec  = 729

2 minutes = 2,187

2 min 15 sec = 6,561

2 min 30 sec = 19,683

2 min 45 sec = 59,049

3 minutes = 177,147