Please answer showing all working

I need to find the answer to an exponential growth formula with the formula Qt=Qo(b)^t
where Qt=quantity after time t, Qo is the original quantity and b= the growth rate

I need to work out t where Qt=0.02g, Qo=0.0005g and b =2

So in summary, can someone please work out the t value in the following equation showing full working

0.02=0.0005 (2)^t

THANKYOU

0.02 = 0.0005 2^t
-> 2^t = 0.02/0.0005
-> 2^t = 40
-> log2 2^t = log2 40
-> t = log2 40
-> t = log 40 / log 2 = 5.321928

take logs,

log(Qt) = log(Qo) + tlog(b) Notice that this is linear of form q = mt + c if we take q = log(Q)
gradient m = log(b) and interecpt -q = c = log(Qo)

log(0.02) = log(0.0005) + t log(2)
t log(2) = log(0.02) - log(0.0005) = log(0.02/0.0005) = log(2/0.05) = log(40)
=1 + 2log(2) .. 2^2.(10)
t = 2+ 1/log(2) =exactly ...or 5.32 units of time.