Acollege-entrance exam is designed so that scores are normally distributed with a mean of 500 and a standard deviation of 100. using the eight‐part symmetry of the area under a normal curve, what is the probability that a randomly chosen exam score is less than 200 or greater than 800? the probability

The probability is  0.003

Step-by-step explanation:

We know that the average is:

The standard deviation is:

The Z-score is:

We seek to find

For P(x>800) The Z-score is:

The score of Z = 3 means that 800 is 3 standard deviations from the mean. Then by the rule of the 8 parts of the normal curve, the area that satisfies the conficion of 3 deviations from the mean has percentage of 0.15%

So

For P(x<200) The Z-score is:

The score of Z = -3 means that 200 is 3 standard deviations from the mean. Then by the rule of the 8 parts of the normal curve, the area that satisfies the conficion of 3 deviations from the mean has percentage of 0.15%

So

Therefore

40 minutes

step-by-step explanation:

add the time and multiply by 2