Determine whether the relation is a function. (4,0), (4,1), (5,2), (6,3), (6,4)
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Answer: The fire is 3.5 miles from tower B
Step-by-step explanation: Please refer to the attached diagram. The triangle in the attached diagram illustrates the clues given in the question. Both rangers are standing at points A and B respectively with a distance of 5 miles between them, which is line AB. Also, one ranger spots a fire from a tower at an angle of 42 degrees, which is point A. Another ranger spots the same fire from another tower, but from an angle of 64 degrees, which is point B. The fire is at point C on the triangle. Now we have a triangle with only one side known (5 miles) and three angles known (the third angle is computed as 180 - {64+42} which equals 74) which are 64 degrees, 42 degrees and 74 degrees.
The distance from the fire to tower B is calculated using the law of sines. (Note that this is not a right angled triangle, hence we cannot use trigonometric ratios). The law of sines is expressed as follows;
a/SinA = b/SinB or
a/SinA = c/SinC
Depending on the sides and angles we are given and the ones we are to calculate.
The distance from the fire to tower B is line BC, labeled as a in our diagram. Using the law of sines
a/SinA = c/SinC
(Note also that a is directly facing angle A, c is directly facing angle C, and so on)
a/SinA = c/SinC
a/Sin 42 = 5/Sin 74
By cross multiplication we now have
a (Sin 74) = 5 (Sin 42)
Divide both sides of the equation by Sin 74 and we now arrive at
a = 5 (Sin 42)/Sin 74
a = 5 (0.6691)/0.9613
a = 3.3455/0.9613
a = 3.4802
{rounded to the nearest tenth of a mile, a equals 3.5}
Therefore the distance from tower B to the fire is approximately 3.5 miles
Conditional Probability
Given two events A and B (not excluding), the probability that A occurs given that B has occurred is called a <em>conditional probability</em> and is calculated as:
Where P(A∩B) is the probability that A and B occur simultaneously and P(B) is the probability that B occurs.
Now with the given data, we must find the values of the required probabilities.
30% of the students play a sport (S), this means that:
70% of the students don't play a sport (NS).
65% of the students have a job.
Note that there could be students who both play sports and have a job.
Of the 30% of the students who play a sport, 50% have a job. This means that:
15% of the students play a sport and don't have a job
15% of the students play a sport AND have a job
65% - 15% = 50% of the students have a job and don't play a sport
That last number is the numerator of the equation given above:
P(A∩B) = 0.5
The event B corresponds to students that don't play a sport (NS), thus:
P(B) = 0.7
Thus we have:
The required probability is 5/7 or 0.7143