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Finding Area Under the Standard Normal Curve Right of a Z-score

 

Example: Find the area under the standard normal curve to the right of

 

In this example of the standard normal curve, we will calculate the area to the right of Z=-0.46.

 

Method 1:  Normalcdf(lowerbound, upperbound, ) computes the area between a lowerbound and an upperbound.  In this example, you are computing the area from -0.46 to positive infinity.  Positive infinity is specified by 1 2nd [EE] 99  (Note:  EE is found above the comma , ).

 

To calculate the area to the right of -0.46, press 2nd [DISTR] and select 2:normalcdf( and type

in -0.46 , 1E99 , 0 , 1 ) and press ENTER.

 

 

Method 2:  This method calculates the area and also displays a graph of the probability distribution.  Press WINDOW and set Xmin equal to -3 and set Xmax equal to 3.  Set Xscl equal to 1.  Set Ymax = .5.  Set Ymin = .5/4.  Press 2nd [QUIT].  Clear all the previous drawings by pressing 2nd [DRAW] and selecting 1:ClrDraw and pressing ENTER ENTER.  Press 2nd [STATPLOT] and TURN OFF all PLOTS.  Now you can draw the probability distribution.  Press 2nd [DISTR].  Highlight DRAW and select 1:ShadeNorm( and type in -0.46 , 1E99 , 0 , 1 ) and press ENTER.  The output displays a normal curve with the appropriate area shaded in and its value computed.