Weights & Measurement

An electronic balance has a readability of 0.1 mg. What does this specification alone establish?

The displayed mass changes in increments of 0.1 mg

The reference mass is 200mg, but the observed mass is 188mg. What are the signed error and absolute percentage error?

-12 mg and 6.0%

A uniform mixture is prepared from 180 mg of drug and 360 mg of lactose. A 270 mg aliquot is taken to prepare 30 capsules, each containing 3 mg of drug and a total powder fill of 200 mg. How much additional lactose must be added to this aliquot before filling the capsules?

5,730

Using the textbook balance model, a balance has a sensitivity requirement (SR) of 6 mg. What is its minimum weighable quantity if the allowed error is 3%?

200 mg

Using the textbook SR error model. 90 mg is weighed on a balance with SR = 6mg. What is the estimated percentage error, and does the measurment meet a 5% error limit? Round the error to one decimal place.

6.7%; no

You need to measure 2.0 mL with an allowed error of 5%. A mL cylinder has an estimated absolute deviation of 0.0075 mL; a 10 mL cylinder has an estimated absolute deviation of 0.109 mL. Based on these estimates, which cylinder meets the error limit?

Only the 5 mL cylinder

T/F: Repeated measurements can be precise even when they are consistently different from the reference value.

Ture

T/F: In the aliquot method, the aliquot may be weighed below the minimum weighable quantity as long as the initial drug mass is above that minimum.

False