Please help, need advise. Thanks

Question

A
The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with = 110 grams and = 25 grams. What is the probability that a randomly selected vitamin will contain less than 100 grams of pyridoxine? ì ó

B
The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with = 110 grams and = 25 grams. Approximately 83% of the vitamins will have at least how many grams of pyridoxine? ì ó

Answer 1

I believe you copied these questions incorrectly. The first one only makes sense if you meant:
The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with (mean) = 110 grams and (standard deviation) = 25 grams. What is the probability that a randomly selected vitamin will contain less than 100 grams of pyridoxine?

You also left out the words "mean" and "standard deviation" in the second question.

Both questions can be answered with normal distribution tables or computational tools.

Answer 2

For a time-saving computational tool for problems like this, see
http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html

I get 34.5% for your first question and 86 grams for the second. The second has to be solved by iteration (seeing what works)

Answer 3

Thanks a lot