One way ..
Using 3 empty cols to the right
Put in H1: =RAND()
Put in I1: =INDEX(E$1:E$50,RANK($H1,$H$1:$H$50))
Copy I1 to J1
Select H1:J1, copy down to J50
Cols I and J will return a full random shuffle
of the times recorded / stock prices in cols E & F
(Pressing F9 will re-generate another random shuffle)
Just plot the 1st 30 pairs of values in cols I & J (i.e. I1:J30)
If required, freeze cols I & J with an-place:
Copy > Paste special > Check "Values" > OK