According to a commercial, 4 out of 5 dentist recommend a certain brand of toothpaste. Suppose There are 120 dentist in your area. What is the expected number of dentist who recommend the brand? What is the standard deviation? Needing assistance with calculating the standard deviation please.

Math it's appreciated. (picture provided)

Someone answer asap for ! max recorded the heights of 500 male humans. he found that the heights were normally distributed around a mean of 177 centimeters. which statements about max’s data must be true? a. the median of max’s data is 250 b. more than half of the data points max recorded were 177 centimeters. c. a data point chosen at random is as likely to be above the mean as it is to be below the mean. d. every height within three standard deviations of the mean is equally likely to be chosen if a data point is selected at random.

When a valve is open 281 gallons of water go through it in one hour the number of gallons that would go through in 94 hours is