At a cell phone assembly plant, 78% of the cell phone keypads pass inspection. A random sample of 104 keypads is analyzed. Find the standard deviation
A) 0.96
B) 0.78
C) 0.22
D) 0.041

Question

At a cell phone assembly plant, 78% of the cell phone keypads pass inspection. A random sample of 104 keypads is analyzed. Find the standard deviation 
A) 0.96 
B) 0.78 
C) 0.22 
D) 0.041

Quizplus · Accepted Answer

To find the standard deviation, we use the formula for the standard deviation of a binomial distribution: 
standard deviation = sqrt(p*(1-p)/n), where p is the proportion of successes (in this case, the proportion of keypads that pass inspection, which is 0.78) and n is the sample size (which is 104). 
Plugging in the values, we get: 
standard deviation = sqrt(0.78*(1-0.78)/104) = 0.041 
Therefore, the answer is D.

At a Cell Phone Assembly Plant, 78% of the Cell