Answer:To calculate the standard deviation of those numbers:
1.Work out the Mean (the simple average of the numbers)
2.Then for each number: subtract the Mean and square the result.
3.Then work out the mean of those squared differences.
4.Take the square root of that and we are done!
Step-by-step explanation:
There is a strong, negative relationship between outside temperature and snow shovel sales. As x increases, y decreases.
Mu=80, sigma=39, X=85
Z=(X-mu)/sigma = 5/39=0.128=0.13
P(X<=85)= 0.5517 (from Z-table)
so, P(X>85)=1-0.5517=0.4483 approx. thats 44.8% probability.
To solve this problem, let us first assign some
variables. Let us say that:
x = pigs
y = chickens
z = ducks
From the problem statement, we can formulate the
following equations:
1. y + z = 30 --->
only chicken and ducks have feathers
2. 4 x + 2 y + 2 z = 120 --->
pig has 4 feet, while chicken and duck has 2 each
3. 2 x + 2 y + 2 z = 90 --->
each animal has 2 eyes only
Rewriting equation 1 in terms of y:
y = 30 – z
Plugging this in equation 2:
4 x + 2 (30 – z) + 2 z = 120
4 x + 60 – 2z + 2z = 120
4 x = 120 – 60
4 x = 60
x = 15
From the given choices, only one choice has 15 pigs. Therefore
the answers are:
She has 15 pigs, 12 chickens, and 18 ducks.
