3.66666666666667 thats what i get
First piece is x
second piece is y. y=4x
third piece is z. z=3y=12x
x+y+z=680
x+4x+12x=680
17x=680. x=40cm y=160cm. z=480cm
Answer:


And using a calculator, excel ir the normal standard table we have that:

And we can calculate the probability like this:
Step-by-step explanation:
A random sample of 36 observations has been drawn from a normal distribution with mean 50 and standard deviation 12. Find the probability that the sample mean is in the interval 47<=X<53. Is the assumption of normality important. Why?
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the variable of interest of a population, and for this case we know the distribution for X is given by:
Where
and 
Since the distribution for X is normal then we know that the distribution for the sample mean
is given by:

We can find the probability required like this:


And using a calculator, excel ir the normal standard table we have that:

And we can calculate the probability like this:

Correct!
no matter what value we enter in for x, the statement will always be incorrect
3(1)=3(1)+4
3 = 3+4
3

7
Answer:
4.3lb
Step-by-step explanation:
4.3lb is more precise out of the answer choices of 4lb and 4.3lb because 4.3lb is an exact weight whereas 4lb could be rounded.