The question is essentially asking about the number of times a dice has been rolled on two separate equations. The information that we are provided takes the form of probabilities, the relationships between these probabilities and the relationship between the number of rolls.
The question states that the probability that the agate stone appears when the dice is thrown \(P\) times, is \(x\) and that the probability the same stone appears when the dice is thrown \(Q\) times, is \(y\). We know that there are six sides to the dice and therefore the probability of it landing on agate can be expressed as \(\frac{1}{6}\). The probability that the dice lands on agate twice in two throws is \(\frac{1}{6}\) * \(\frac{1}{6}\) or \(\frac{1}{36}\). The probability then for landing on agate \(N\) times in \(N\) throws then, would be expressed as \((\frac{1}{6})^N\) or simply \(\frac{1}{6^N}\) since we know that \(N\) must be a positive integer.
Based of this, we can express the probabilities \(x\) and \(y\) as follows.
\(x = \frac{1}{6^P}\) and \(y = \frac{1}{6^Q}\)
We also know that \(x < y\) and that \(\frac{1}{x} + \frac{1}{y} = 7,992\)
Now all we need to do is plug in the values for \(x\) and \(y\) and we get \(\frac{1}{1/6^P} + \frac{1}{1/6^Q} = 7,992\) or expressed simpler, \(6^P + 6^Q = 7,992\).
Since we know that P and Q must be positive integers between 1 and 6, it is not very difficult to work out this equation. We can quickly calculate the first powers of 6:
\(6^1=6 ; 6^2=36 ; 6^3=216 ; 6^4=1296, 6^5=7776\). No need to calculate further as 7,776 is quite close to 7,992 and there is no posibility that it will be \(6^6\). Since there are only two integers we are adding we know that one value must be larger than half of 7,992, which in this case is 7776 or \(6^5\). The second value we can calculate by subtracting 7,776 from 7,992 which is 216 or \(6^3\). Therefore \(6^5+6^3=7992\)
Now we just need to assign \(P\) and \(Q\) to the right values. To help with that, we have one piece of key information in that \(x < y\). The larger \(P\) is the smaller \(x\) will be and the smaller \(Q\) is the larger \(y\) will be therefore \(P>Q\) must be true.
Of the two values, 5 is larger than 3 and so \(P=5\) and \(Q=3\)
Bunuel
The king of Trishkinda has specially designed an ivory dice. Six exotic stones – agate, jasper, chalcedony, sapphire, topaz, garnet – are embedded on the six sides of the dice, such that one side has exactly one type of stone and no two sides have the same type of stone. When the dice is rolled, the probability of the agate stone appearing is \(\frac{1}{6}\). Let there be values P, Q, x, y such that when the dice is thrown P times, the probability of the agate stone appearing all P times is x and when the dice is thrown Q times, the probability of the agate stone appearing all Q times is y. Furthermore, \(x < y\) and \(\frac{1}{x} + \frac{1}{y} = 7,992\).
In the table, select a value for P and a value for Q that are jointly consistent with the given information. Make only two selections, one in each column.