Answer:
(3)
Step-by-step explanation:
the sum of n and 5 is (n + 5), then multiply by 3 gives
3(n + 5)
The result is at least 17 which means it must be greater than or equal to 17
3(n + 5) ≥ 17
Answer:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:

Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the variable of interest of a population, and for this case we know the distribution for X is given by:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:

Answer:
1395 is the lower bound because 1395 rounded to the nearest 10 is 1400 but 1394 rounded to the nearest 10 is 1390.
Step-by-step explanation:
Answer:
4.8
Step-by-step explanation:
Answer:
16 runners
Step-by-step explanation:
you have to add up all the runners that are under 13 minutes. Which is, 8+6+2 = 19 runners