Question

Abdullah is a quality control expert at a factory that paints car parts. He knows that 20\ , percent of parts have an error in their painting. He recommended a change in the painting process, and he wanted to see if this error rate had changed. He took a random sample of 400400400 parts painted in a month and found that 606060 had an error.

Answer 1

The error rate has decreased after changing the painting process.

Step-by-step explanation:

Abdulla knows that 20 percent of the parts have an error in their painting. After suggesting changes in painting process, he wants to know whether the error rate has changed.

Number of parts in the random sample=400400400

Number of parts that had an error=606060

We have to determine what percentage of 400400400 is 606060

$606060=x/100 \times 400400400\\=0.15%$

After changing the painting process 0.15% of parts have error.

The previous percentage was 20.Hence the error rate has clearly changed.