The percentage of the runners having times less than 14.4 sec is 0.15%. Then the correct option is A.
It is also called the Gaussian Distribution. It is the most important continuous probability distribution. The curve looks like a bell, so it is also called a bell curve.
The z-score is a numerical measurement used in statistics of the value's relationship to the mean of a group of values, measured in terms of standards from the mean.
The times of all 15 years old who run a certain race are approximately normally distributed with a given mean μ = 18 sec and standard deviation σ = 1.2 sec.
The percentage of the runners has times less than 14.4 sec.
Then the z-score will be given as
[tex]\rm z = \dfrac{X - \mu}{\sigma }\\\\\\z = \dfrac{14.4 - 18}{1.2}\\\\\\z = -3[/tex]
Then the percentage will be
[tex]\rm P(z < -3)=0.00135 = 0.135 \% \approx 0.15 \%[/tex]
More about the normal distribution link is given below.
https://brainly.com/question/12421652
