Answer:
I hope this helps a little bit
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:

Answer:
7 1/2 miles
Step-by-step explanation:
1 1/2 miles in every 1/5 hour
x miles in 1 hour
x equals 1 times 1 1/2 divided by 1/5
x equals 5 times 1 1/2
x equals 7 1/2
Answer:

Step-by-step explanation:
Recall that since X is uniformly distributed over the set [1,4] we have that the pdf of X is given by
if
and 0 otherwise. In the same manner, the pdf of Y is given by
if
and 0 otherwise.
Note that if Y is in the interval (4,5] then Y>X by default. So, in this case we have that P(Y>X| y in (4,5]) = 1. We want to calculate the probability of having Y in that interval . That is
. Thus,
.
We want to proceed as follows. Using the total probability theorem, given two events A, B we have that
In this case, A is the event that Y>X and B is the event that Y is in the interval (4,5].
If we assume that X and Y are independent, then we have that the joint pdf of X,Y is given by
when
. We can draw the region were Y>X and the function h(x,y) is different from 0. (The drawing is attached). This region is described as follows:
and
, then (the specifics of the calculations of the integrals are ommitted)
Thus,

Answer:
x=-3
Step-by-step explanation:
3(x-6)+6=5x-6 - Problem
The Distributive property says a(b+c)=ab+ac. Using this knowledge, lets solve.
1) Distribute 3 to x and -6:
3x-18+6=5x-6
2) Combine alike terms: (-18 and 6)
3x-12=5x-6
3) Subtract 3x from both sides:
-12=2x-6
4) Add 6 to both sides:
2x=-6
5) Divide both sides by 2:
x=-3