Do you get statistics?

A Sample survey interviews an SRS of 267 women. Suppose 70%of women have dieted over the past 12 months. What is the probability that 75% or more of the women in the sample have been on a diet?








I am really confused and would really appreciate any help you can give me. And any tips to understanding statistics in general would be greatly appreciated.


Thanks!

Do you get statistics?
An essential piece of solving this puzzle is knowing the standard deviation associated with the number of women who have dieted (assuming the number of women who dieted is distributed normally). Low standard deviation means the sample is unlikely to deviate from the 70% mean. So, for example, if the standard deviation is high then the probability that 75% of the women in the sample have been on a diet will be large as compared to if the standard deviation is low.





According to Wikipedia: "Standard deviation may serve as a measure of uncertainty. In physical science for example, the reported standard deviation of a group of repeated measurements should give the precision of those measurements. When deciding whether measurements agree with a theoretical prediction, the standard deviation of those measurements is of crucial importance: if the mean of the measurements is too far away from the prediction (with the distance measured in standard deviations), then we consider the measurements as contradicting the prediction. This makes sense since they fall outside the range of values that could reasonably be expected to occur if the prediction were correct and the standard deviation appropriately quantified."
Reply:X ~ Normal( μx = p , σx² = p*(1-p)/n )


X ~ Normal( μx = 0.7 , σx² = 0.0007865169 )


X ~ Normal( μx = 0.7 , σx = 0.02804491 )





Find P( X %26gt; 0.75 )


P( ( X - μ ) / σ %26gt; ( 0.75 - 0.7 ) / 0.02804491 )


= P( Z %26gt; 1.782855 )


= 0.03730497 Report Abuse


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