We start by showing the position of the first quartile, Q1 on the normal distribution graph. Q1 happens at 25% of the data.
The graph is shown below
We are interested in the area to the left of Q1 and we know that the probability is 0.25
We can find out the value of z-score from the table as shown below
The z-score when p=0.25 is 0.68
then changing this z-score into the actual value
The graph is shown below
We are interested in the area to the left of Q1 and we know that the probability is 0.25
We can find out the value of z-score from the table as shown below
The z-score when p=0.25 is 0.68
then changing this z-score into the actual value