# Groovy, <s>158</s> 143 characters

<!-- language: lang-groovy -->

    d={new Date().getTime()}
    s=d(j=0)
    8.times{Thread.start{b=d(m=1000)
    sleep 8*m
    synchronized(j){j+=d()-b}}}addShutdownHook{print([(d()-s)/m,j/m])}

Sample run:

    bash-4.3$ groovy wait1minute.groovy
    [8.031, 64.055]