A recent survey found adults over 50 wear glasses. In a random sample of 50 adults over 50, what is the mean and standard deviation of the number who wear glasses?
2007-11-01 03:05:26 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
This is all the question provided, I know the answer mean 32.5, and std 3.37. I was hoping to get an answer that explains the process of getting this answer rather than another question.
2007-11-01 03:22:14 · update #1
oh I forgot to percentage, sorry, 65% of adults over 50 wear glasses.
2007-11-01 03:23:12 · update #2
Perhaps that recent survey found that a certain percent of adults over 50 wear glasses? You would need to know that number.
Express that percent as a decimal, and call the decimal "p". ( e.g., if 75% wear glasses, then p=.75)
If n= the number of individuals in the random sample, then
mean number who are expected to wear glasses = np
standard deviation = sqrt(np[1-p])
I'm sure you can work out the arithmetic.
2007-11-01 03:24:56 · answer #1 · answered by Michael M 7 · 0⤊ 0⤋
The proportion of people who wear glasses is 65/100 or 0.65.
mean = np , n=50(number of samples) p=0.65
mean =50(0.65) =32.5
Standard deviation = sqrt([np(1-p)]
=sqrt[50(0.65)(0.35]=3.37
2007-11-01 03:52:04 · answer #2 · answered by cidyah 7 · 0⤊ 0⤋
Why don't you tell us since you know the data (presumably) and we don't.
2007-11-01 03:11:32 · answer #3 · answered by Anonymous · 0⤊ 0⤋