Question

A study of 120,000 randomly selected photos posted to a social media site determined that 4% were "selfies," photos of oneself. If the percent of selfies is consistent throughout the rest of the photos on the site, and there are 20 billion photos, how many billions of photos on the site are selfies?

Answer 1

0.8 billion of photos on the site are selfies.

Explanation:

This problem can be solved by a simple rule of three.

A study of 120,000 randomly selected photos posted to a social media site determined that 4% were "selfies," photos of oneself. This means that for 1 photo, 0.04 are selfies.

There are 20 billion photos, how many billions of photos on the site are selfies?

1 - 0.04

20 - x

`x = 20*0.04`

`x = 0.8`

0.8 billion of photos on the site are selfies.