VeritasKarishma wrote:
harshbirajdar wrote:
I am still not understanding the one SD less than mean logic. Why should it be less and not more than 77.6?
VeritasKarishma can you help me out, please?
harshbirajdarMean =100 (on calculation)
What is the meaning of 1 SD below mean? This is what it means graphically:
Attachment:
546e68776bb3f74f68b7d0ba.jpeg
For a normal distribution (usually this is what we deal with), 68% values lie within 1 SD of mean (34% below mean and 34% above mean)
95% values lie within 2 SD etc.
So if mean of a normal distribution is say 100 and SD is say 25, there will be 34% values lying within 75 to 100 and 34% values within 100 to 125.
The data might look something like this: ... 50,
76, 78, 93,
102, 115, 120, 134 ...
3 values lying in 1 SD below mean and 3 values lying in 1 SD above mean.
In a question like this (we don't have to worry whether it is a normal distribution), we can find the mean and we are given the SD.
1 SD below mean would be values lying between 77.6 and 100.
"more than one SD below the mean" would be values lying below 77.6 (they are lying within 2 SD or 3 SD or 4 SD...)
There are only 2 such values.
Hi
VeritasKarishma - A quick follow up on this chart specifically.
The question is asking about how many values are there in set below the Mean - 1 standard deviation threshold
Per the graph, there should be only 16 % of the values in any normal distribution { (100 - 68)/2 }
Thus i thought only 16 % of the value in the set
Given the set is 10 elements, 16 % of 10 is 1.6 values
Thus i thought, well we cant have 1.6 values, so i chose 1 value because i thought there will certainly be only one value. 2 values is above 1.6
Why doesn't this logic work
Thank you for everything !