SOLUTION: Use the normal distribution of SAT critical reading scores for which the mean is 512 and the standard deviation is 113. Assume the variable x is normally distributed. left parenth

Algebra.Com
Question 1044667: Use the normal distribution of SAT critical reading scores for which the mean is 512 and the standard deviation is 113. Assume the variable x is normally distributed.
left parenthesis a right parenthesis(a)
What percent of the SAT verbal scores are less than 675​?
left parenthesis b right parenthesis(b)
If 1000 SAT verbal scores are randomly​ selected, about how many would you expect to be greater than 575​?

Answer by rothauserc(4718)   (Show Source): You can put this solution on YOUR website!
a) z-score = (X - mean) / std dev = (675 - 512) / 113 = 1.4424 approx 1.44
:
we consult the table of Z-values for our z-score
:
**********************************************
Probability(P) ( X < 675 ) = 0.9251 approx 93%
**********************************************
:
b) sample is 1000 and sample mean is the same as population mean = 512
sample std. dev. = std. dev / square root(sample size) = 113 / square root(1000) = 3.5733 approx 3.57
:
P ( X > 575 ) = 1 - P ( X < 575 )
:
z-score = (575 - 512) / 3.57 = 17.6471 approx 17.65
:
P ( X < 575 ) = 100% or 1.00
:
***************************************************
We expect no SAT scores > 575 in our sample of 1000
***************************************************
:

RELATED QUESTIONS

Use the normal distribution of SAT critical reading scores for which the mean is 501 and... (answered by Boreal)
Use the normal distribution of SAT critical reading scores for which the mean is 509 and... (answered by Boreal)
Use the normal distribution of SAT critical reading scores for which the mean is 515 and... (answered by Boreal)
5.2.17 Use the normal distribution of SAT critical reading scores for which the mean (answered by Boreal)
There are two major tests of readiness for college, the ACT and the SAT. ACT scores... (answered by Boreal)
The college board reported the following mean scores for teh three parts of the SAT.... (answered by stanbon)
Scores on the SAT form a normal distribution with a mean score of 500 and a standard... (answered by Theo)
Scores on the SAT form a normal distribution with an average of 500 and a standard... (answered by ewatrrr)
Supposed the data are SAT scores and follow a normal distribution with a mean of 500 and... (answered by Theo)