PS....
"joeu2004" wrote:
Enter the following formula into A1:A10000:
=CHOOSE(MATCH(RAND(),{0,0.05,0.15,0.8,0.95}),RANDB ETWEEN(1,10),
RANDBETWEEN(11,20),RANDBETWEEN(21,60),RANDBETWEEN( 61,85),
RANDBETWEEN(86,100))

Despite appearances, only two random functions are calculated for each cell.
CHOOSE only evaluates the parameter selected by MATCH.