Enter X Enter μ or X Enter σ or s Enter n
      Click here if you already know your z-score  

First, we need to calculate a Z-score. The formula is denoted below:
Using the Normal Distribution, Calculate P(X < 15.89)

Z  =  X - μ
  σ/√33

Z  =  15.89 - 16.2
  2.9/√33

Z  =  -0.31
  2.9/5.744562646538

Z  =  -0.31
  0.50482520227152

  Z  =  -0.614

From the table below, we see that our Z value is = 0.229069

The z-table probability runs from 0 to z and -z to 0, so we lookup our value
From the table below, we find our value of 0.229069
Since that represents ½ of the graph, we subtract our value from 0.5 → 0.5 - 0.229069
P(x<-0.614) = 0.270931

  00.010.020.030.040.050.060.070.080.09
000.0040.0080.0120.0160.01990.02390.02790.03190.0359
0.10.03980.04380.04780.05170.05570.05960.06360.06750.07140.0753
0.20.07930.08320.08710.0910.09480.09870.10260.10640.11030.1141
0.30.11790.12170.12550.12930.13310.13680.14060.14430.1480.1517
0.40.15540.15910.16280.16640.170.17360.17720.18080.18440.1879
0.50.19150.1950.19850.20190.20540.20880.21230.21570.2190.2224
0.60.22570.22910.23240.23570.23890.24220.24540.24860.25170.2549
0.70.2580.26110.26420.26730.27040.27340.27640.27940.28230.2852
0.80.28810.2910.29390.29670.29950.30230.30510.30780.31060.3133
0.90.31590.31860.32120.32380.32640.32890.33150.3340.33650.3389
10.34130.34380.34610.34850.35080.35310.35540.35770.35990.3621
1.10.36430.36650.36860.37080.37290.37490.3770.3790.3810.383
1.20.38490.38690.38880.39070.39250.39440.39620.3980.39970.4015
1.30.40320.40490.40660.40820.40990.41150.41310.41470.41620.4177
1.40.41920.42070.42220.42360.42510.42650.42790.42920.43060.4319
1.50.43320.43450.43570.4370.43820.43940.44060.44180.44290.4441
1.60.44520.44630.44740.44840.44950.45050.45150.45250.45350.4545
1.70.45540.45640.45730.45820.45910.45990.46080.46160.46250.4633
1.80.46410.46490.46560.46640.46710.46780.46860.46930.46990.4706
1.90.47130.47190.47260.47320.47380.47440.4750.47560.47610.4767
20.47720.47780.47830.47880.47930.47980.48030.48080.48120.4817
2.10.48210.48260.4830.48340.48380.48420.48460.4850.48540.4857
2.20.48610.48640.48680.48710.48750.48780.48810.48840.48870.489
2.30.48930.48960.48980.49010.49040.49060.49090.49110.49130.4916
2.40.49180.4920.49220.49250.49270.49290.49310.49320.49340.4936
2.50.49380.4940.49410.49430.49450.49460.49480.49490.49510.4952
2.60.49530.49550.49560.49570.49590.4960.49610.49620.49630.4964
2.70.49650.49660.49670.49680.49690.4970.49710.49720.49730.4974
2.80.49740.49750.49760.49770.49770.49780.49790.49790.4980.4981
2.90.49810.49820.49820.49830.49840.49840.49850.49850.49860.4986
30.49870.49870.49870.49880.49880.49890.49890.49890.4990.499

NOTE: To get in Microsoft Excel using your z-score, enter the formula =NORMSDIST(-0.614)

P(x<-0.614) = 0.270931