The test scores at Millbrook High School are normally distributed, and the 60th percentile is equal to a score of 70.
Quantity A :
The 30th percentile score
Quantity B :
35
Answer in the book is D i.e cannot be determined … but following the steps greg showed in the normal distribution youtube video : Need help with a GRE Problem? October 6, 2019 (Riding the Normal Distribution rollercoaster) - YouTube
The answer should be A right? Please help u guys
For following the steps in that video you need at least one more known percentile
Otherwise you can’t really use it
How did you arrive at A?
the 60th percentile is 70 . so the 30th percentile would have been 35 had this been a rectangular distribution , but since this is a normal distribution the 30th percentile would be further shifted towards the mean right … so shouldnt that be greater than 35
What would it be if the mean was let’s say 45?
If the mean was 45, the 40th percentile would be 20
and the 30th percentile would definitely be lower than 35
What would it be if the mean was let’s say 65?
If the mean was 65, the 40th percentile would be 60
and the 30th percentile would definitely be higher than 35
You don’t know the maximum marks, you don’t know the minimum marks, the average, the median, pretty much nothing
Ohh … i get it now … way too little info to do anything with huh … cool … thanks for the reply