Answer:
(y + 7i)(y - 7i)
Step-by-step explanation:
It cannot be factored using real numbers, but consider
7i × - 7i
= -49i² and i² = - 1
= 49
The factoring as a difference of squares to obtain
y² + 49 = (y + 7i)(y - 7i)
? can be any number except for 3 or -2 as it is already used in (3,4), (-2,-5)
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 ![[2499;2510]](https://tex.z-dn.net/?f=%5B2499%3B2510%5D)
. From inference theory we know that :
Now we can find the probability as follows:
Where 
, then:
