Question

WILL MEDAL


(SAT) scores are normally distributed with a mean of 500 points and a standard deviation of 100 points. Suppose you take the SAT and several weeks later you receive a letter telling you that your results on the math portion of the test were in the 90th percentile.

Recalling that SAT scores are always expressed as multiples of 10, how many points did you get on the test?

A 690
B 600
C 590
D 130
E 630

Answer 1

@satellite73

Answer 2

sorry i don't know any statistics at all

Answer 3

@SolomonZelman

Answer 4

@jim_thompson5910

Answer 5

@karatechopper

Answer 6

@Kainui

Answer 7

do you have a calculator?

Answer 8

No

Answer 9

go here

https://www.prometric.com/en-us/clients/SOA/Pages/calculator.aspx

and type in 0.9 into the box next to N(x) under the "INVERSE CDF CALCULATOR"

Answer 10

this will give you the value of k such that \(\Large P(Z \le k) = 0.9\) is true

Answer 11

Is says x is 1.28155

Answer 12

So that means

\[\Large P(Z \le 1.28155) \approx 0.9\]

Answer 13

we know that z = 1.28155

Answer 14

mu = 500 is the population mean
sigma = 100 is the population standard deviation

Answer 15

z = 1.28155
mu = 500
sigma = 100


plug those values into


z = (x - mu)/sigma


and solve for x

Answer 16

X=628.155

Answer 17

round that to the nearest tens place

Answer 18

630?

Answer 19

correct

Answer 20

you do that because "SAT scores are always expressed as multiples of 10"

Answer 21

Oh ok thank you

Answer 22

no problem