Question

A​ quality-control inspector examined 100 light bulbs and found 7 defective. At this​ rate, how many defective bulbs would there be in a lot of 3000 ​bulbs?

Answer 1

we are given that out of 100 light bulbs, 7 of them were defective. We can assume that out of every 100 lightbulbs, 7 of them will be defective.

we can write this as a ratio of defective lightbulbs to total

7:100

we want to see how many defective there are when we have 3000 bulbs, to do this we can multiply both numbers by 30

7 * 30 = 210

100 * 30 = 3,000

our new ratio is now

210:3,000

so we are now able to say that in a lot of 3,000 lightbulbs, there would be 210 defective bulbs.

hope this helped!