Answer:
10
Step-by-step explanation:
If there is a direct relation between two variables x and y then it can be represented as
y = kx ,
where y is dependent variable
x is independent variable
k is constant of variation
_____________________________
First condition
y = 400
x = r
using y = kx then relationship will be
400 = kr
finding k here
k = 400/r
Second condition
y = r
x = 4
using y = kx then relationship will be
r = 4k
finding k
k = r/4
since in both condition equation is same
thus, value of k will also be same
thus,
400/r = r/4
=> 400*4 = r*r
=> 1600 = r^2

Thus, 40 is the value of r
k = r/4 = 40/4 = 10
Thus, constant of variation is 10 which is correct choice.
To cross validate
k = 400/r = 400/40 = 10
That is the Identity Property of Addition.
If it is adding and the whole number stays the same it is Identity Property of Addition.
If it is multiplying then it would be the Identity Property of Multipulcation. For example for this problem it would be 6x1 in multipulcation in which the whole number would stay the same.
Here are descriptions of all the properties:
https://wikis.engrade.com/mathproperties1
Answer:
-3x-6y-2z
Step-by-step explanation:
(4x - 2y)-(7x+4y-2z) = 4x-2y-7x-4y-2z = -3x-6y-2z
I hope that's the answer.
The sound intensity of the Pile Driver is 39.5
or nearly 40 times the sound intensity of the jackhammer.
Given with Loudness in dB for pile driver = 112 dB
We have to convert it in terms of sound intensity.
First,
112dB/10 = 11.2
Then we'll use this as exponent of 10
(10)^(11.2) = 1.5849 * 10 ^ 11
Then use the equation of Watts per square meter to find the intensity:
I / (10^-12 W/m^2) =1.5849 * 10 ^ 11
I = sound intensity = 0.158
Then compare:
Sound intensity of Pile Driver/ Sound intensity of Jackhammer
(0.158) / (0.004)
= 39.5
or nearly 40 times the jackhammer.
Economic Order Quantity
The economic order quantity, that is, the order quantity that minimizes the inventory cost is:
300 cases of tennis balls
Data and Calculations:
Sales of tennis balls for the coming year = 10,000 units
Carrying (holding) costs per case = $10
Cost of placing orders with the manufacturer = $45 per order
Economic Order Quantity (EOQ) = square root of (2 * Annual Demand/Sales * Ordering cost)/Carrying cost per case
= square root of (2 * 10,000 * $45)/$10
= square root of 90,000
= 300 tennis balls
This implies that the distributor will place about 33 orders in the coming year. With each order, the quantity placed is 300 units. This is the economic order quantity that will minimize its inventory cost for the year.