Answer:
a. P(X>695)=0.026
b. P(X<485)=0.44
Step-by-step explanation:
The question is incomplete:
a. higher than 695 on the test.
b. at most 485 on the test.
We have a normal distribution with mean 500 and standard deviation of 100 for the test scores. We will use the z-scores to calculate the probabilties with the standard normal distribution table.
a. We want to calculate the probability that a randomly selected student scores higher than 695.
We calculate the z-score and then we calculate the probability:
[tex]z=\dfrac{X-\mu}{\sigma}=\dfrac{695-500}{100}=\dfrac{195}{100}=1.95\\\\\\P(X>695)=P(z>1.95)=0.026[/tex]
a. We want to calculate the probability that a randomly selected student scores at most 485.
We calculate the z-score and then we calculate the probability:
[tex]z=\dfrac{X-\mu}{\sigma}=\dfrac{485-500}{100}=\dfrac{-15}{100}=-0.15\\\\\\P(X<485)=P(z<-0.15)=0.44[/tex]
