Q.1 The park's sprinklers can spray 1,748 gallons of water on the grass in 38 minutes. How many gallons can they spray in one mi
2 answers:
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Let be the randomly selected lengths. Without loss of generality, suppose
where are independent random variables with the same uniform distribution on [0, 1].
By their mutual independence, we have
so that the joint density function is
where is the cube with vertices at (0, 0, 0) and (1, 1, 1).
Consider the plane
with . This plane passes through (0, 0, 0), (1, 0, 1), and (0, 1, 1), and thus splits up the cube into one tetrahedral region above the plane and the rest of the cube under it. (see attached plot)
The point (0, 0, 1) (the vertex of the cube above the plane) does not belong the region , since
. So the probability we want is the volume of the bottom "half" of the cube. We could integrate the joint density over this set, but integrating over the complement is simpler since it's a tetrahedron.
Then we have
Answer:
The expected value of betting $500 on red is $463.7.
Step-by-step explanation:
There is not a fair game. This can be demostrated by the expected value of betting a sum of money on red, for example.
The expected value is calculated as:
being G the profit of each possible result.
If we bet $500, the possible outcomes are:
- <em>Winning</em>. We get G_w=$1,000. This happens when the roulette's ball falls in a red place. The probability of this can be calculated dividing the red slots (half of 36) by the total slots (38) of the roulette:
- <em>Losing</em>. We get G_l=$0. This happens when the ball does not fall in a red place. The probability of this is the complementary of winning, so we have:
Then, we can calculate the expected value as:
We expect to win $463.7 for every $500 we bet on red, so we are losing in average $36.3 per $500 bet.