the sat and act college entrance exams are taken by thousands of students each year. the mathematics portions of each of these exams produce scores that are ap- proximately normally distributed. in recent years, sat mathematics exam scores have averaged 480 with standard deviation 100. the average and standard deviation for act mathematics scores are 18 and 6, respectively.

Here we have been mentioned that in the recent years, sat maths exam scores have averaged 480 with standard deviation 100. the average and standard deviation for act mathematics scores are 18 and 6, respectively.

a) The percentage of the students scoring below 550 marks in a typical year is calculated as follows:

Let x be the SAT score

So, x follows normal distribution

Given above,

mean (μ) = 480

standard deviation (σ) = 100

we will find P ( x < 550)

We will use the excel function NORM.DIST to find the required probability

P(x < 550) = NORM.DIST[tex](550, 480, 100, TRUE)[/tex]

= 0.7580

= 75.80%

Hence the percentage of the students who are scoring below 550 in a typical year = 75.80%

b) We calculate the score to be set by the engineering school as a comparable standard on the ACT math test as follows:

Let Z be the ACT score

Z follows the normal distribution

Given above, μ = 18 and σ = 6

Let Z' be the ACT score comparable to the standard set for SAT

Then we need to find Z' such that P(Z < Z') = 75.80% = 0.758

From standard normal tables we get Y' such that

Z' = NORM.INV[tex](0.758, 18, 6)[/tex]

= 22.2

The ACT score that needs to be set by the college = 22.2 marks

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