Final answer:
In both options 1 and 2, the expected number of ads in 100 news stories is 4. Option 2 yields a probability of 1.75% for exactly one ad, and 1.70% for no ads.
Step-by-step explanation:
Expected Number of Ads in News Stories
For option 1, where 1 out of every 25 stories is an ad, the expected number of ads shown in 100 news stories would be 4, as 100 divided by 25 equals 4.
For option 2, with a 4% chance of any story being an ad, the expected number of ads shown in 100 news stories would be 100 multiplied by 0.04, which is also 4.
Probability of Viewing a Specific Number of Ads
To calculate the probability of a user being shown only a single ad in 100 stories with option 2, we use the binomial probability formula:
P(X=1) = (100 choose 1) * (0.04)^1 * (0.96)^99
This equals approximately 0.0175, or 1.75%.
The chance of no ads being shown at all can be calculated as (0.96)^100, which equals approximately 0.0170, or 1.70%.