18.00 + 8.50 + 8.50 + 8.50 + 8.50 = 52.00
So that's 4 Friends
Answer:

Step-by-step explanation:
Let x be the distance from the foot of the ladder to the base of the building.
We have a right triangle, so we can use Pythagoras' Theorem.

remember that when multiplying indices, you add the powers. When dividing indices, remember that you subtract the powers. When taking the power of a number which has already been raised to a power, you must multiply the values of these powers. Any value raised to the power of 0 is equal to 1.
Answer:
Step-by-step explanation:
1) 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".
Let X the random variable that represent the scores, and for this case we know the distribution for X is given by:
And let
represent the sample mean, the distribution for the sample mean is given by:
On this case
2) Calculate the probability
We want this probability:
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: