A ratio of 5:7 means out of 12 books, 5 are in one category and 7 are in another. (The “category” isn’t specified in this problem.)
So here we’re STARTING with 36 books; we want to find a ratio that is equal to 5:7 and adds up to 36. Well 36 = 3(12), and so if we multiply each number in the ratio by 3 as well, we might get what we want. Doing that gives us 15:21, which adds up to 36 and is equal to 5:7. Boom, that’s the answer.
P.S. Here’s a question you can think about: why do ratios stay the same when you multiply each number by the same amount? (For example, why is 3:1 the same as 6:2?)
Answer:
The pressure is changing at 
Step-by-step explanation:
Suppose we have two quantities, which are connected to each other and both changing with time. A related rate problem is a problem in which we know the rate of change of one of the quantities and want to find the rate of change of the other quantity.
We know that the volume is decreasing at the rate of
and we want to find at what rate is the pressure changing.
The equation that model this situation is

Differentiate both sides with respect to time t.

The Product rule tells us how to differentiate expressions that are the product of two other, more basic, expressions:

Apply this rule to our expression we get

Solve for 

when P = 23 kg/cm2, V = 35 cm3, and
this becomes

The pressure is changing at
.
Answer:
b
Step-by-step explanation:
Answer:
The correlation coefficient of the data is -0.13, which means as the weekly mileage increases, it has no effect on the average mile time.Step-by-step explanation:
The correlation coefficient of a data set describes how closely related two variables are. Correlation coefficients close to positive 1 show a strong positive correlation, while correlation coefficients close to negative 1 show a strong negative correlation. When a correlation coefficient is close to 0, it shows no correlation between the data.
For the given data set, calculate the correlation coefficient using technology.
This r-value is closer to 0 then it is to -1. Thus, the correlation coefficient of the data is -0.13, which means as the weekly mileage increases, it has no effect on the average mile time.
For reference, one full circle is 360 degrees or 2pi radians.
If we were to convert 360 degrees to radians, we could set up the following equation:
360k = 2pi
where k is a constant. By solving for k, we can find what value we must multiply any angle in degrees by to get its radian counterpart.
Divide both sides by 360:
k = 2pi/360
Reduce:
k = pi/180
So to convert an angle from degrees to radians, multiply it by pi/180. For example, 120 degrees would be:
120 * pi/180 = 2pi/3 radians