Question 1169655
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67% of the children do not have cavities
p = 0.67 is the probability of selecting a child who does not cavities.


n = 70 is the sample size


mu = mean
sigma = standard deviation


For a binomial distribution it has the following formulas
mu = n*p 
sigma = sqrt( n*p*(1-p) )


Let's first find the mean
mu = n*p 
mu = 70*0.67
mu = 46.9
The mean is exactly 46.9


Now the standard deviation
sigma = sqrt( n*p*(1-p) )
sigma = sqrt( 70*0.67*(1-0.67) )
sigma = 3.93408184968233
sigma = 3.93
The standard deviation is approximately 3.93


Answers:
mean = 46.9
standard deviation = 3.93
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