On your TI-84
normalcdf(65,67,68.5,1.7)
0.169037441
About 16.9%
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To get normalcdf, press 2nd, VARS, 2
If you see this, make it read:
lower:65
upper:67
μ:68.5
σ:1.7
Paste
Scroll to highlight "Paste", then press enter
Edwin