Work out: 2/7 + 3/7 =? 5/8 + 7/8 =? 2/3 - 1/2 =?
2 answers:
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Answer:
E (Y) = 3
Step-by-step explanation:
If a 4-sided die is being rolled repeatedly; and the odd-numbered rolls (1st 3rd,5th, etc.)
The probability of odd number roll will be, p(T) =
However, on your even-numbered rolls, you are victorious if you get a 3 or 4. Also, the probability of even number roll, p(U) =
In order to calculate: E (Y); We can say Y to be the number of times you roll.
We know that;
E (Y) = E ( Y|T ) p(T) + E ( Y|U ) p(U)
Let us calculate E ( Y|T ) and E ( Y|U )
Y|T ≅ geometric =
Y|U ≅ geometric =
also; x ≅ geometric (p)
∴ E (x) =
⇒ = 4 ; also
= 2
E (Y) = 4 × + 2 ×
= 2+1
E (Y) = 3