Answer:
4.243
Step-by-step explanation:
To calculate the diagonal of a square, multiply the length of the side by the square root of 2:
d = a√2
d = 3√2=4.24264068
The mean is the sum of all numbers divided by the number of numbers. We can set up an equation:

Where 'x' is the next quiz score she need. Solve for 'x'. Multiply 5 to both sides:

Add:

Subtract 322 to both sides:

So her next quiz score needs to be 73 in order to have a mean score of 79 on all her quizzes.
Until the concerns I raised in the comments are resolved, you can still set up the differential equation that gives the amount of salt within the tank over time. Call it

.
Then the ODE representing the change in the amount of salt over time is



and this with the initial condition

You have


![\dfrac{\mathrm d}{\mathrm dt}\left[e^{t/250}A(t)\right]=\dfrac25e^{t/250}(1+\cos t)](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cmathrm%20d%7D%7B%5Cmathrm%20dt%7D%5Cleft%5Be%5E%7Bt%2F250%7DA%28t%29%5Cright%5D%3D%5Cdfrac25e%5E%7Bt%2F250%7D%281%2B%5Ccos%20t%29)
Integrating both sides gives


Since

, you get

so the amount of salt at any given time in the tank is

The tank will never overflow, since the same amount of solution flows into the tank as it does out of the tank, so with the given conditions it's not possible to answer the question.
However, you can make some observations about end behavior. As

, the exponential term vanishes and the amount of salt in the tank will oscillate between a maximum of about 100.4 lbs and a minimum of 99.6 lbs.
Answer:
(a+b)(a-b)
Step-by-step explanation:
because (a+b)(a-b):
If you use FOIL it will work backwards
Answer:
750 minutes
Step-by-step explanation:
Let the number of minutes be represented as x
1 cent = 0.01
Beetle cellular offers cellular phone service for 39.95 a month plus one cent a minute.
$39.95 + 0.01x
Salamander digital offers cellular phone service for 9.95 a month plus five cents a minute.
$9.95 + 0.05x
How many minutes would a person need to use a month for beetle cellular to cost the same as salamander digital?
This is calculated as:
Beetle cellular = Salamander digital
$39.95 + 0.01x = $9.95 + 0.05x
Collect like terms
$39.95 - $9.95 = 0.05x - 0.01x
$30.00 = 0.04x
x = $30.00/0.04
x = 750 minutes
A person need to use 750 minutes a month for beetle cellular to cost the same as salamander digital.