Respuesta :
Answer:
the answer is D
Step-by-step explanation: so you know that he can do 9 topics in 45 minutes. which is 1 topic every 5 minutes when you divide 45/9. if there is 60 minutes in an hour, and he does 1 topic every 5 minutes, he would do 12. hope this helps xd
A teacher can cover 12 topics in a 1-hour period. It is given that the number of topics he can cover is directly proportional to the length of the time he has to review. So, option D is correct.
How the variables are said to be directly proportional?
Two variables are said to be directly proportional if one variable increases/decreases with respect to the increase/decrease in the other variable. They are related to each other by proportionality.
A ∝ B (A and B are two variables)
⇒ A2/A1 = B2/B1
How the given variables are related?
The given variables are 'N - number of topics' and 'T - time period'.
It is given that they are directly proportional to each other.
So, we can write
N ∝ T
⇒ N2/N1 = T2/T1
Calculation:
Given that,
A teacher can cover 9 topics in a single 45-minute period.
So, N1 = 9 topics and T1 = 45 minutes
And T2 = 1 hour
We need to find N2 =?
Thus, from the above equation
N2/N1 = T2/T1
⇒ N2/9 = (1 hour)/45 minute
1 hour = 60 minutes
⇒ N2/9 = (60/45)
⇒ N2 = 9 × 4/3
∴ N2 = 12 topics
So, he can cover 12 topics in 1 hour. Thus, option D is correct.
Learn more about proportionality here:
https://brainly.com/question/13354953
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