Question

The distribution of weights of newborn babies is bell shaped with a mean of 3200 grams and standard deviation of 450 grams.

a. what percentage of newborn babies weigh between 2300 and 4100 grams?

I have already done part A

Part b asks What percentage of newborn babies weigh less then 2300 grams?

I need to know how to do that on a ti84 plus calculator

Answer 1

Solution:

Given: The distribution of weights of newborn babies is bell shaped with a mean of 3200 grams and standard deviation of 450 grams.

That is: and

Part b) We have to find : percentage of newborn babies weigh less then 2300 grams?

That is: P( X < 2300) =..........?

Use following steps in TI-84 plus calculator:

Step 1) Press 2ND and then press VARS button

Step 2) Select normalcdf(

Step 3) We need to enter the numbers:

Lower Limit = -1E99

Upper limit = 2300

Paste.

Note: to enter lower limit , press (-) button which is in the bottom of calculator , then type 1 , then press 2ND and press COMMA button to get E then type 99

-1E99 means that lower limit is minus infinity

If if it not working, just do another way:

press (-) button then type 9999999999999999

Now click on Paste and press ENTER key two times to get answer.

Thus P( X < 2300 ) =0.02275

P( X < 2300 ) = 0.02275 X 100

P( X < 2300 ) = 2.275%

P( X < 2300 ) = 2.28%

Thus 2.28% of newborn babies weigh less then 2300 grams.