Answer:
40
Step-by-step explanation:
36 = 90% × (number of questions)
36/0.90 = (number of questions) = 40 . . . . . divide by the coefficient of the variable
There were 40 questions on the test.
Answer:
10 million (10,000,000) tens can go into 100,000,000
Answer:
60 stamps
Step-by-step explanation:
Has 33 now. Before adding 13 stamps, she had (33-13) 30. This is half of her total, since she already sold half. To get the whole, multiply 30 by 2. 60 She started with 60
How many stories does it have?
Answer:
![51.72\text{ cells per hour}](https://tex.z-dn.net/?f=51.72%5Ctext%7B%20cells%20per%20hour%7D)
Step-by-step explanation:
So, the function, P(t), represents the number of cells after t hours.
This means that the derivative, P'(t), represents the instantaneous rate of change (in cells per hour) at a certain point t.
C)
So, we are given that the quadratic curve of the trend is the function:
![P(t)=6.10t^2-9.28t+16.43](https://tex.z-dn.net/?f=P%28t%29%3D6.10t%5E2-9.28t%2B16.43)
To find the <em>instanteous</em> rate of growth at t=5 hours, we must first differentiate the function. So, differentiate with respect to t:
![\frac{d}{dt}[P(t)]=\frac{d}{dt}[6.10t^2-9.28t+16.43]](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%5BP%28t%29%5D%3D%5Cfrac%7Bd%7D%7Bdt%7D%5B6.10t%5E2-9.28t%2B16.43%5D)
Expand:
![P'(t)=\frac{d}{dt}[6.10t^2]+\frac{d}{dt}[-9.28t]+\frac{d}{dt}[16.43]](https://tex.z-dn.net/?f=P%27%28t%29%3D%5Cfrac%7Bd%7D%7Bdt%7D%5B6.10t%5E2%5D%2B%5Cfrac%7Bd%7D%7Bdt%7D%5B-9.28t%5D%2B%5Cfrac%7Bd%7D%7Bdt%7D%5B16.43%5D)
Move the constant to the front using the constant multiple rule. The derivative of a constant is 0. So:
![P'(t)=6.10\frac{d}{dt}[t^2]-9.28\frac{d}{dt}[t]](https://tex.z-dn.net/?f=P%27%28t%29%3D6.10%5Cfrac%7Bd%7D%7Bdt%7D%5Bt%5E2%5D-9.28%5Cfrac%7Bd%7D%7Bdt%7D%5Bt%5D)
Differentiate. Use the power rule:
![P'(t)=6.10(2t)-9.28(1)](https://tex.z-dn.net/?f=P%27%28t%29%3D6.10%282t%29-9.28%281%29)
Simplify:
![P'(t)=12.20t-9.28](https://tex.z-dn.net/?f=P%27%28t%29%3D12.20t-9.28)
So, to find the instantaneous rate of growth at t=5, substitute 5 into our differentiated function:
![P'(5)=12.20(5)-9.28](https://tex.z-dn.net/?f=P%27%285%29%3D12.20%285%29-9.28)
Multiply:
![P'(5)=61-9.28](https://tex.z-dn.net/?f=P%27%285%29%3D61-9.28)
Subtract:
![P'(5)=51.72](https://tex.z-dn.net/?f=P%27%285%29%3D51.72)
This tells us that at <em>exactly</em> t=5, the rate of growth is 51.72 cells per hour.
And we're done!