probability question The standard normal Z table at httpwwws

probability question

The standard normal (Z) table at http://www.sjsu.edu/faculty/gerstman/EpiInfo/z-table.htm contains, for each value of Z from 0 to about 3, the area under the standard normal curve N(0, 1) to the left of x = Z. As discussed in class, this area can be interpreted as the probability that a value selected at random from the standard normal distribution (mean µ = 0, standard deviation = 1) will be less than or equal to Z. Using only this table and the fact that any normal distribution N(µ, ) is a rescaling of the standard normal distribution, answer the following questions.

Question: Look at the table of 2013 SAT score percentiles at

Data below :

http://media.collegeboard.com/digitalServices/pdf/research/SAT-Percentile-Ranks-2013.pdf

Based on this table, assuming that no further re-centering or re-norming of scores has taken place since 1995,

a) have students as a whole become better or worse at taking the test?

b) Which section is currently “harder”: math or verbal?

please Justify your answers in light of the data in the table.

the link does work and these are all the info i have for this question.

Solution

students as a whole became better at taking the test as below them is atleast 1 indicating they are above those not taking the test.

b) Maths is harder as average is highest with 514 but std dev almost the same