Answer: c. during several storms, there were five hours of delay for every eight hours of rain
Step-by-step explanation: i just had this question
Answer: 17.89
Step-by-step explanation:
In binomial distribution, the standard deviation is given by :-

As per given , we have
The number of vouchers in the sample with errors is denoted by x.
p= 0.20 , n = 2000
Then , 

Hence, the standard deviation of x is 17.89.
X = burger number. 3x-6 = fries sold
3x-6 = 120 solve for x