I got an answer of 6.4% when following the equation to calculate utilization. I thought this would be correct. What am I missing?

Assume a TCP sender is continuously sending 1,212-byte segments. If a TCP receiver advertises a window size of 8,063 bytes, and with a link transmission rate 41Mbps an end-to-end propagation delay of 18.7ms, what is the utilization? Assume no errors, no processing or queueing delay, and ACKs transmit instantly. Also assume the sender will not transmit a non-full segment. Give answer in percentages, rounded to one decimal place, without units (e.g. for an answer of 10.43% you would enter "10.4" without the quotes)