<h3><u>
Answer:</u></h3>
<em>Hence,</em>
<em>
</em>
<h3><u>
Step-by-step explanation:</u></h3>
There are total 9 databases.
Only 5 of these databases contain the given keyword.
we have to find the probability that it will be found in at least 2 of the first 4 searched databases.
So, we will use the binomial to find this probability.
<em>We know that the probability of r successes out of the n outcomes is calculated as:</em>
<em>
</em>
<em>Where p denote the probability of success.</em>
<em>and </em>
<em>
</em>
p=5/9 ( since out of the 9 databases 5 contain the given keyword)
1-p=4/9.
so, we have to find:

Here n=4
Also,




Hence, the probability is calculated by adding equation (1),(2) and (3).
Hence,
