I generally know how to use the normalcdf function on my calculator, but how to I find the area under a normal curve if there is no lower limit or no upper limit? For instance, we are required to use a calculator on this problem:
Find the area under the standard normal curve that corresponds to the z values to the left of 1.55.
The upper limit would be 1.55, but what do I put for the lower limit?
negative infinity?
To find the area under a normal curve using a calculator when you have an upper limit but no lower limit, you can use the normalcdf function with a lower limit of negative infinity.
Here's how you can do it step by step:
Step 1: Press the appropriate key on your calculator to access the normalcdf function. The exact key may vary depending on the calculator model, but it is usually the "2nd" or "VARS" key followed by "DISTR" or "DISTR/2nd" key.
Step 2: Enter the upper limit value as 1.55. This represents the z-value to the left of which you want to find the area.
Step 3: For the lower limit, enter "-∞" (negative infinity). This indicates that there is no lower limit, and you want to consider all the area to the left of the upper limit.
Step 4: Enter the mean and standard deviation of the standard normal distribution, which are 0 and 1 respectively.
Step 5: Press the "Enter" or "Calculate" key to compute the area under the standard normal curve to the left of 1.55.
The calculator will give you the desired result, which represents the area under the standard normal curve that corresponds to the z-values to the left of 1.55.