some diffences appear in my answer
1.in q 1(b), my approach is Ho=90,H1<90, so tobs =-2<-1.6604,reject
2.in q 1(d), my p-value is p(Z>1)=1-0.8413=0.1587
3.q 1(e), my p is p(absolute Z>0.73)=0.2327*2=0.4654
4.in (f), mine is Ho=80, H1>80, tobs is 1.22, the p-value isp(Z>1.22)=1-0.8888=0.1112