Answer:
We conclude that the mean is greater than 25.
Step-by-step explanation:
We are given the following in the question:
Population mean, μ = 25
Sample mean,
= 27
Sample size, n = 100
Alpha, α = 0.05
Sample standard deviation, s = 6.5
First, we design the null and the alternate hypothesis

We use One-tailed(right) z test to perform this hypothesis.
Formula:

Putting all the values, we have

Now, 
Since,

We reject the null hypothesis and accept the alternate hypothesis.
Thus, the mean is greater than 25.