Solution: We know that height of trees follows a normal distribution with mean height inches and standard deviation inches
Now let's fill the missing values as per the normal distribution and the given information.
Now, let's find the value of a1. Since the height follows normal distribution with mean 60 and standard deviation = 12. Therefore, we have:
To find the value of a2, we need to use the empirical rule of normal distribution. According to empirical rule, the area between Mean and 1 standard deviation above mean is 34.1%. Therefore, the value of a2 is:
a3 denotes the area between +1 and +2 (72 to 84 inches). According to empirical rule of normal distribution, the area between one standard deviation above mean and two standard deviation mean is 13.6%.
And
Therefore, the complete table is attached here.