Answer:
The discriminant of f is 92, and it has no real zeros
Step-by-step explanation:
The discriminant of a quadratic is , where the quadratic is in the form
. The discriminant of this one is therefore:
Since the square root of a negative number is imaginary, this quadratic has no real number zeros. Hope this helps!
The empirical rule you're referring to is the 68-95-99.7 rule, which asserts that for a normal (bell-shaped) distribution, approximately 68% of the distribution lies within 1 standard deviation of the mean; 95% lies within 2 standard deviations of the mean; and 99.7% lies within 3 standard deviations of the mean.
Let be the random variable denoting vehicle speeds along this highway. We want to find
. To use the rule, we need to rephrase this probability in terms of the mean and standard deviation.
Notice that , and
. In other words, 61 and 79 both lie exactly 3 standard deviations away from the mean, so
.
