Question

Quality control finds on average that 0.026% of the items from a certain factory are detective. One month, 4000 items are checked. How many items are expected to be detective?

Answer 1

Given that 4000 items are checked in one month, let the number of detective items be represented as y.

Quality control finds on average that 0.026% of the items in the factory are detective. This implies that

$\text{Number of }\det ective\text{ items = }\frac{\text{0.026}}{100}\times\text{Total number of items checked}$

When 4000 items are checked, we have the number of detective items to be evaluated as

$\begin{gathered} \text{Number of }\det ective\text{ items = }\frac{\text{0.026}}{100}\times\text{Total number of items checked} \\ y=\frac{0.026}{100}\times4000 \\ \Rightarrow y=1.04 \end{gathered}$

Hence, the number of detective items is 1.04.