October 13, 2008
If you flipped three pennies, what would be the odds that they all came out the same?
Ok... Odds are different from probability
Probability(x) = (Chances for)/(Total chances)
Odds, on the other hand, are given as:
(Chances for) : (Chances against)
So if these are the following solutions:
TTT (000)
TTH (001)
THT (010)
THH (011)
HTT (100)
HTH (101)
HHT (110)
HHH (111)
There are 2/8 solutions that satisfy this. So 1/4 would be the PROBABILITY, but they asked for ODDS which would be 2:6 or 1:3
Monday, October 13, 2008
Sunday, October 12, 2008
How to solve the 2 cars math problem
If two cars were faced away from each other back to back, both cars travelled 8 miles forward then made a 90 degree left turn and traveled another 6 miles, how far apart would they be?
Possible answers (as given on question):
� Right next to each other.
� 48km
� 32km
� I'm not sure / Hey, there's no SKIP button
First we must find how far each car went. If the beginning point is (0,0) on a coordinate plane, the the car on the right went to point (8,6) and the car on the left went to point (-8,-6). They for a diagonal line on opposite sides of the plane so option A (Right next to each other is wrong). We want to find the length of the diagonal so we do the following.
a^2 + b^2= c^2 (the Pythagorean theorem)
a= to the distance on the x axis (or 8) and b= to the distance on the y axis (or 6). Remember, you cannot have negative distance, so even though on of the cars is in the negative portion of the plane, it still went positive distance. C= the unknown diagonal length.
a^2 + b^2= c^2
8^2 + 6^2= c^2
64 + 36 = c^2
100 = c^2
sqrt(100)= sqrt(c^2)
10 = c
c= 10
They are 20 miles away from each other. However, the answers are in km so we convert from mi to km.
1 mile is, approximately, 1.6 km so we do the following:
1 mi/1.6 km = 20 mi/ X km, cross multiply
X= 32
So the distance between the two cars is approximately 32 km, or answer C.
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