Answer:
a) 0.3571 = 35.71% probability that the stock price will be more than $25.
b) 0.1429 = 14.29% probability that the stock price will be less than or equal to $18.
Explanation:
Uniform probability distribution:
An uniform distribution has two bounds, a and b.
The probability of finding a value of at lower than x is:

The probability of finding a value between c and d is:

The probability of finding a value above x is:

Uniformly distributed between $16 and $30 per share.
This means that

a) More than $25?

0.3571 = 35.71% probability that the stock price will be more than $25.
b) Less than or equal to $18?

0.1429 = 14.29% probability that the stock price will be less than or equal to $18.