posted by Katy on .
The College Board, which are administered each year to many thousands of high school students, are scored so as to yield a mean of 550 and a standard deviation of 100. these scores are close to being normally distributed. what percentage of the scores can be expected to satisfy each condition?
Can you check these answers first?
greater than 600 =30.853
greater than 750=2.275
less than 400=6.681
between 400 and 600=62.465
what score represents Q3?
what score separates the top 70% from the bottom 30% ?
Z = (score-mean)/SD
Z = (600-550)/100 = 50/100 = .5 = 30.85%
>750 = 2.28%
< 400 = 6.68%
>440 and < 600 = 62.47
Apparently your table has 5 decimal places.
Use the table to find the Z scores for .75 and .30 and insert those in the equation above.