Hello!
We have two probabilities we can use; we have 170/400, for our experiment, and 1/2, which is our theoretical probability.
To solve, we just multiply the two probabilities.
[tex] \frac{170}{400}(1/2) [/tex]=0.2125≈21.3
Therefore, we have about a 21.3% chance of this event occurring.
I hope this helps!
