α=P(Xbar<=11|μ=12)=Φ(xbar-μ/(δ/根号n))=Φ(11-12/0.8)=0.1056 (说白了就是xbar服从N(μ,δ方/n)在μ=12时,求P(xbar<=11)的概率)
同理,求P(Xbar>=11|μ=10)
Φ(11-12/(4/根号n))<=0.05,求下得n=44
α=P(Xbar<=11|μ=12)=Φ(xbar-μ/(δ/根号n))=Φ(11-12/0.8)=0.1056 (说白了就是xbar服从N(μ,δ方/n)在μ=12时,求P(xbar<=11)的概率)
同理,求P(Xbar>=11|μ=10)
Φ(11-12/(4/根号n))<=0.05,求下得n=44