01
Press these keys
2nd→VARS→DISTR→invNorm(
Step 1 of 4. Press 2nd.
02
Walkthrough
- 1Convert to left area
invNorm uses the area to the left. A top 10% cutoff therefore uses area 0.90.
- 2Enter parameters
Use invNorm(area,μ,σ) and select LEFT/CENTER/RIGHT if your OS wizard presents a tail option.
- 3Verify
Substitute the result into normalcdf to confirm the intended probability.
03
Worked example
X~N(70,10²). Find the 90th percentile.
NORMAL FLOAT AUTO REAL MP
invNorm(.9,70,10)82.81551566AnswerApproximately 82.8.