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27 votes
27 votes
I don’t have much time left for this timed homework. pleas only help if ur fast

I don’t have much time left for this timed homework. pleas only help if ur fast-example-1
User Jeremy Bell
by
2.7k points

1 Answer

12 votes
12 votes

Let x be the random variable representing the test score of a student. Since the scores are normally distributed and the population mean and standard deviation are known, we would apply the formula which is expressed as

z = (x - mean)/standard deviation

From the information given,

mean = 82

standard deviation = 5.85

For a student that scored below 71, the probability is expressed as

P(x < 71)

We would find the z score using the formula stated above

x = 71

z = (71 - 82)/5.85 = - 1.88

We would find the probability value corresponding to a z score of - 1.88 from the normal distribution table. The value is 0.03

Thus,

P(x < 71) = 0.03

Since there are 40 students in the class, the number of students that scored below 71 would be

0.03 * 40

= 1.2

That is approximately 1 student

The correct option is the second one

User JDx
by
3.2k points
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