Question 1200058
<font color=black size=3>
Part H


The gap from 23 to 29 is 6 units
The gap from 8 to 29 is 21 units
6/21 = 0.2857 approximately is the probability of being to the right of 23, given we automatically know we're to the right of 8.


The answer to part H should be 0.2857


It's curious how your teacher got 0.7143


My guess is that s/he mistakenly did 1-0.2857 = 0.7143
Or perhaps your teacher meant to ask "Find the probability that the time is <font color=red size=4>less</font> than 23 minutes given (or knowing that) it is at least 8 minutes."
</font>