Question

A quality control manager at a factory selects $7$ lightbulbs at random for inspection out of every $400$ lightbulbs produced. At this rate, how many lightbulbs will be inspected if the factory produces $20,000$ lightbulbs?

• A. 300
• B. 350
• C. 400
• D. 450

Answer 1

The correct option is B 350

$7$ lightbulbs are selected out of every $400$ manufactured bulbs.

Since the total manufactured bulbs are $20,000;$ the number of lightbulbs that will be inspected becomes $\frac{7}{400}\times 20,000$

$=7\times 50$

$=350$