Practice problems

# Question
1 The maximum percentage error allowed is 5 % and the balance states the sensitivity requirement is 6 mg. What is the minimum weighable quantity?
2 What is the maximum percentage error in weighing 65 mg of drug on a balance with a sensitivity requirement of 6 mg?
3 A pharmacist weighs 639 mg of a substance on a balance, he then weighs it again on a more sensitive balance. Second balance reads 200 mg. Calculate the percentage error in the original weighing. Is this percentage error acceptable according to the USP standards?
4 Calculate the SR of a prescription balance if 15 mg on this balance was able to move the pointer by 2 divisions. Does this satisfy class A prescription balance requirement?

Answers

The Answer to question 1 is: 120.00 mg

The Answer to question 2 is: 9.2 %

The Answer to question 3 is: 68.7 %; No not acceptable as it is more than 5 %

The Answer to question 4 is: a) 7.50 mg b) No, this does not satisfy Class A prescription requirement.