Answer:
36 minutes
Step-by-step explanation:
10blocks in 6mins
20blocks in 12mins
30blocks in 18mins
40blocks in 24mins
50blocks in 30mins
60blocks in 36mins
<h2>
Answer:</h2>
The probability is:

<h2>
Step-by-step explanation:</h2>
It is given that:
An urn contains balls numbered 1 through 20.
A ball is chosen, returned to the urn, and a second ball is chosen.
This means that this is a case of a replacement.
Hence, one of the event is independent of the other.
Now we know that the probability to get a particular number of ball is:

( Since, there are total 20 balls and a ball of one particular number is just unique )
i.e. 
Hence, the probability that the first and second balls will be a 8 is:

<h2>You need a reflection across the y-axis!</h2>
Answer:
10% probability that a given class period runs between 51.25 and 51.75 minutes.
Step-by-step explanation:
An uniform probability is a case of probability in which each outcome is equally as likely.
For this situation, we have a lower limit of the distribution that we call a and an upper limit that we call b.
The probability of finding a value X between c and d, d greater than c, is given by the following formula:

Uniformly distributed between 49 and 54 minutes
This means that 
Find the probability that a given class period runs between 51.25 and 51.75 minutes.

10% probability that a given class period runs between 51.25 and 51.75 minutes.