**TI89**mainRvarconfiИеZ.() Prgm ClrIO Disp "sample size" Input m Disp "sample variance" Input s Disp "confidence level" Input r m-1n If r<.95 Then n-1.5*и(2*n)y n+1.75*и(2*n)z Else If r<.98 Then n-1.6*и(2*n)y n+2.15*и(2*n)z Else If r<.99 Then n-1.96*и(2*n)y n+2.65*и(2*n)z Else n-2.1*и(2*n)y n+2.9*и(2*n)z EndIf EndIf EndIf Define y1(x)=s\Chi2CdfF(0,x,n) nSolve(y1(x)=(1-r)/2,x=y)q nSolve(y1(x)=(1+r)/2,x=z)t (m-1)s/qb (m-1)s/ta ClrIO Disp "variance interval" Disp {round(a,4),round(b,4)} Disp "deviation interval" Disp {round(и(a),4),round(и(b),4)} EndPrgm фх▄Цд