Average Top 50 Percentile Values in an Array

one way i can think of
for case 4567
=SUMPRODUCT(LARGE($A$1:$A$10,ROW(INDIRECT("1:"&ROUNDUP(COUNTA($A$1:$A$10)/2,0))))/(ROUNDUP(COUNTA($A$1:$A$10)/2,0)))
for case 567
=SUMPRODUCT(LARGE($A$1:$A$10,ROW(INDIRECT("1:"&ROUNDDOWN(COUNTA($A$1:$A$10)/2,0))))/(ROUNDDOWN(COUNTA($A$1:$A$10)/2,0)))