Since 18 is one twentieth of the angle of a full circle, 360, the circumference is 20 times the arc distance of 15, or 300
Answer:

And for this case we know this condition:

By the complement rule we know that:

But since the distribution is symmetrical we know that:

So then the statement for this case is FALSE.
b. False
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
For this case if we define the random variable of interest X and we know that this random variable follows a normal distribution:

And for this case we know this condition:

By the complement rule we know that:

But since the distribution is symmetrical we know that:

So then the statement for this case is FALSE.
b. False
Answer:
6:8 and 9:12
Step-by-step explanation:
As long as you do the same thing to both parts of the ratio, it's the same ratio