Answer
mean: 587.5
median: 489
mode: none
Work Step by Step
mean
$(451+356+478+776+892+500+467+780)\div8=4700\div8=587.5$
median
$356, 451, 467, 478,\underset\uparrow\ 500, 776, 780, 892$
$(478+500)\div2=978\div2=489$
mode
none - no numbers are repeated in the list