Answer:
Cross Sectional
Step-by-step explanation:
A cross sectional is one in which an association is developed between a risk factor or an outcome.
In the given question the device is used to record the viewing habits of about 2500 households, and the data collected today will be used to determine the proportion of households tuned to a particular news program. There will be risk factor in today's research with the future developed program which will the outcome.
For example there are 20 students in my class who cannot write. So I develop a program to help them write. But the next year there may not be any student who would require such help.So there's a risk factor associated with the outcome.
Cross sectional results are recorded in a two ways table showing do's and don'ts.
Your answer to the first one is incorrect.
We can cut the plan into two figures, a rectangle with side lengths of 4 cm and 5 cm and a rectangle with side lengths of 1 and 2 cm.
Perimeter of a Rectangle:
P = 2(l + w)
P = 2(4 + 5)
P = 2(9)
P = 18
Perimeter of a Rectangle:
P = 2(l + w)
P = 2(2 + 1)
P = 2(3)
P = 6
Add up the perimeters:
18 + 6 = 24
So the total perimeter is 24.
For the 2nd one, your answer is also incorrect.
We multiply 5 to the perimeter of the plans:
5 * 24 = 120
Not sure what the third one is asking.
For the fourth one we just multiply 'k' to the perimeter:
24 * k = 24k
As a fraction: 287/100
As a mixed number: 2 87/100
_____
Remember, "%" means exactly the same thing as "/100".
Answer:
1. 1343 years
2. 9 hours
3. 39 years
Step-by-step explanation:
1. Given, half-life of carbon = 5730 years.
∴ λ = 0.693/half-life of carbon = 0.693/5730 = 0.000121
If N₀ = 100 then N = 85
Formula:- N = N₀*e^(-λt)
∴ 85 = 100 * e^(-0.000121t)
∴㏑(-0.85)=-0.000121t
∴ t = 1343 years
2. Given half-life of aspirin = 12 hours
λ = 0.693/12 = 0.5775
Also N₀ = 100 then 70 will disintegrate and N = 30 will remain disintegrated.
∴ 70 = 100 *e^(-0.05775t)
0.70 = e^(-0.05775t)
㏑(0.70) = -0.05775t
∴ t = 9 hours
3. The population of the birds as as A=A₀*e^(kt)
Given that the population of birds fell from 1400 from 1000, We are asked how much time it will take for the population to drop below 100, let that be x years.
The population is 1400 when f = 0, And it is 1000 when f = 5
We can write the following equation :
1400 = 1000e^(5t).
∴1400/1000 = e^(5k)
∴ k = ㏑(1.4)/5
We need to find x such that 1400/100 = e^(xk)
14 = e^(xk)
∴ x = 39 years
