1) first pick red 5/9 blue 4/9
2) second pick when red has been picked red now becomes 4/8, blue stays 4/8
2) Second pick when blue has been picked blue now becomes 3/8, red stays 5/8
Mind you, you only need both different colours so:
first pick red 5/9 x sec pick blue 4/8 = 20/72
and first pick blue 4/9 x sec pick red 5/8 = 20/72
add both up 20/72 + 20/72 = 40/72 = 5/9
Answer: Choice A)

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Work Shown:

This is not the only way to solve for H.
Answer: (B) 6 floors
Step-by-step explanation: Use the equation -3 + 9 to get the amount of floors above ground level.
-3 + 9 = 6
6 floors.
Answer:
20 degrees
Step-by-step explanation:
I don't know why the 30 degrees was given at point A because you don't need that.
The equation is;
Sinx= Opposite/Hypotneuse
x = Sin inverse (50/146)
= 20.02
Rounded to 20 degrees
Answer:
Option B. The standard deviation of the number of floors per city is nothing.
Step-by-step explanation:
The standard deviation of a data set is the statistic that measures the deviance or dispersion of the data from the relative mean. In other words, it is is a measure of how spread the numbers are. The standard deviation is given by the following formula:

In this case, it is the deviation of the number of floors in the building in the city.