Answer:
The probability that the diameter falls in the interval from 2499 psi to 2510 psi is 0.00798.
Step-by-step explanation:
Let's define the random variable,
"Comprehensive strength of concrete". We have information that
is normally distributed with a mean of 2500 psi and a standard deviation of 50 psi (or a variance of 2500 psi). In other words,
.
We want to know the probability of the mean of X or
that falls in the interval
. From inference theory we know that :

Now we can find the probability as follows:

Where
, then:

Hi
First dont panic. this one is pretty easy.
you known that the perimeter is the addition of every sides of a figure.
you have the total perimeter : 84.6
so now you just have to withdraw every side you have to the total , and the missing measure will be the result.
have a try ! you can make it.