Is this pulse wave question missing something?

Question

Calculate the PRP,PRF,PD,DF, wavelength,SPL of reflector interface and period if a 3 cycles pulse emitted from a 5 MHz transducer if the echo time received was 10ms in soft tissue?

I tried to answer this homework but, I couldn't get the right answer.

PRP = Pulse Repetition Period
PRF = Pulse Repetition Frequency
PD = Pulse Duration
DF = Duty Factor
SPL = Spatial Pulse Length

Answer 1

The duty factor is not specified.
Example
assuming the pulse spacing is such that the signal is off as long as it is on. The time from the beginning of one pulse to the begining of the next is twice the duration of of a single pulse.
PD=3/5,000,000=6E-7
PRP=2*PD=1.2E-6
PRF=1/PRP=8.3E5
SPL=PD*(velocity of the wave)
Different medium have different speed of sound. I don't know the speed of sound in soft tissue. In air it is about 700 Miles per hour or about 1000 feet per second. I would expect the speed to be higher in more dense material.

Answer 2

Well you can definitely get the PD, 3/5e6. But the necessary info for the other parameters doesn't seem to be there unless the PRP depends on the echo time, e.g., if each new transmitted pulse is triggered by the delayed received pulse. With PD and PRP known you could easily find PRF and DF. The SPL could be determined if you knew the velocity of sound in soft tissue; do you?