Three standard dice, one with 4 sides, one with 6 sides, and one with 10 sides are rolled. The probability that all three dice show the same number can be expressed as b a where a and b are positive coprime integers. What is the value of a + b ?
Details and assumptions
A standard i -sided die has sides numbered 1 , 2 , … , i and each rolls with equal probability.
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There are 4 ⋅ 6 ⋅ 1 0 = 2 4 0 possible outcomes. The dice only show the same number when they all show 1 , 2 , 3 , or 4 , for a total of 4 ways. The probability of them all showing the same number is then 2 4 0 4 = 6 0 1 . Adding 1 and 6 0 gives us 6 1 .
Alternatively, "ignore" the first roll.
The 2nd roll has a 6 1 chance of matching the 1st roll, while the 3rd has a 1 0 1 chance of matching. Multiplying these probability gives us the answer.
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i solved the same way.....nice approach.........
There are only 4 ways for all 3 die to show the same number, which is if they show the numbers 1/2/3/4.
In order to calculate the total number of possible outcomes, which is 4 x 6 x 10 =240 outcomes, we need to understand that for every 1 of the 4 numbers displayed on the 4-sided dice, there will be 6 possible numbers for the second dice and 10 for the third dice. Therefore, you should get 240 ways in total.
Thus, 4/240 = 1/60. Sum is 61.
assume that 4 dice.........showed some number .........for others to show same number probability=1/6*1/10=1/60 so=60+1=61
use latex ...... it is quite useful in submitting solutions.
i solved same like that..
Sides that are common = 4 Total Combinations of 4,6 & 10 sided dice are 4 × 6 × 1 0 = 2 4 0
Dividing 2 4 0 4 = 6 0 1 = 1 + 6 0 = 6 1
The number of ways of rolling the three dice is 4 × 6 × 1 0 = 2 4 0 . Although there is only 4 numbers that all three dice share. Hence the probability that they all roll the same number is 2 4 0 4 = 6 0 1 . Therefore a + b = 1 + 6 0 = 6 1 .
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The number of ways to have all dice showing the same number is 4 (they all show 1 , 2 , 3 , 4 ). The total number of outcomes of the dice rolls is 4 ⋅ 6 ⋅ 1 0 = 2 4 0 . Hence P ( a l l t h e s a m e ) = 2 4 0 4 = 6 0 1 Therefore a + b = 1 + 6 0 = 6 1