According to a recent article in the Wall Street Journal, 40% of web surfers who view online pop up ads remember them. Suppose a random sample of 5 web surfers is selected. What is the standard deviation in the number that will remember the ad

The value is  

Step-by-step explanation:

From the question we are told that

  The proportion of people that remember the ad is p =  0.40

   The sample size is  n  =  5

Generally this study of number of web surfers who view online pop up ads and remember them follow binomial  distribution in that the outcome is two (which either they remember them or not) , the number of trial is finite ,  each the two outcome is consistent throughout the study.

Generally the standard deviation in the number that will remember the ad is mathematically represented as

=>    

=>    

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116

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