How to find Vusers using throughout and response time

Recently in an interview I was asked the question, to find Vusers using throughout and response time. Question. Find Vusers for throughout of 1260 bits per second and response time of 2 Milli seconds. The duration of the test we have run to achieve these results is 1 hour.

When I asked he said No thinktime or pacing, so it's zero. So, As per Littles law, i calculated it as response time * throughput 1260*(0.002)=2.52 or 3..He said it's wrong..

Is there anything iam missing here? If yes then please let me know.. Because iam totally confused now..As per the response time as 2 Milli seconds which is rare I think 3 user should be ok..But if iam wrong then what is the correct calculation..