Answer:
12.08
Step-by-step explanation:
For each sunflower, there are only two possible outcomes. Either it germinates, or it does not. The probability of a sunflower germinating is independent of other sunflowers. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The standard deviation of the binomial distribution is:

Seventy-six percent of sunflower seeds will germinate into a flower
This means that 
Samples of 800:
This means that 
The standard deviation for the number of sunflower seeds that will germinate in such samples of size 800 is:

he ratio of 3:1 involves 4 units. 3 men +1 woman.
Find how many people each unit represents:
4units 2476 people
Therefore each unit represents 2476/4 = 619 people per unit
Now, take the ratio, and multiply up:
3:1 => 3619:1619 => 1857:619 You check this is right by adding the two fractions:
1857 men + 619 women = 2476 people therefore, we are correct
The number of men more than women = Number of men - Number of women
= 1857-619 = 1238 and that is your answer
Ok so for every 1 centimeter you get 10 millimeters. Meaning that if you multiply 20 * 10 you get 200 millimeters and if you multiply 10 * 10 you get 100. Now you subtract 200-100 and you get 100 millimeters.