Let r be the interest rate. Then:
1000(1+r/4)^4=1500
(1+r/4)^4=1.5
ln (1+r/4)^4= ln 1.5
4 ln (1+r/4)=ln 1.5
ln (1+r/4)=0.10136627702704109549450327886609
1+r/4=e^0.10136627702704109549450327886609=1.1066819197003215924087902734403
r/4=0.1066819197003215924087902734403
r=0.42672767880128636963516109376133 or 42.67%, compounded quarterly. ☺☺☺☺