Answer is B hope this helped
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Total video games the room can hold
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3 x 40 = 120 video games
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Number of video games he owns
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85
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Number of video games the room can hold
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120 - 85 = 35
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Answer: The room can hold another 35 games
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Answer:
(a) P(X=1)=0.46
(b) E[X]=1.3
Step-by-step explanation:
(a)
Let A be the event that first coin will land on heads and B be the event that second coin will land on heads.
According to the given information
![P(A)=0.6](https://tex.z-dn.net/?f=P%28A%29%3D0.6)
![P(B)=0.7](https://tex.z-dn.net/?f=P%28B%29%3D0.7)
![P(A')=1-P(A)=1-0.6=0.4](https://tex.z-dn.net/?f=P%28A%27%29%3D1-P%28A%29%3D1-0.6%3D0.4)
![P(B')=1-P(B)=1-0.7=0.3](https://tex.z-dn.net/?f=P%28B%27%29%3D1-P%28B%29%3D1-0.7%3D0.3)
P(X=1) is the probability of getting exactly one head.
P(X=1) = P(1st heads and 2nd tails ∪ 1st tails and 2nd heads)
= P(1st heads and 2nd tails) + P(1st tails and 2nd heads)
Since the two events are disjoint, therefore we get
![P(X=1)=P(A)P(B')+P(A')P(B)](https://tex.z-dn.net/?f=P%28X%3D1%29%3DP%28A%29P%28B%27%29%2BP%28A%27%29P%28B%29)
![P(X=1)=(0.6)(0.3)+(0.4)(0.7)](https://tex.z-dn.net/?f=P%28X%3D1%29%3D%280.6%29%280.3%29%2B%280.4%29%280.7%29)
![P(X=1)=0.18+0.28](https://tex.z-dn.net/?f=P%28X%3D1%29%3D0.18%2B0.28)
![P(X=1)=0.46](https://tex.z-dn.net/?f=P%28X%3D1%29%3D0.46)
Therefore the value of P(X=1) is 0.46.
(b)
Thevalue of E[X] is
![E[X]=\sum_{x}xP(X=x)](https://tex.z-dn.net/?f=E%5BX%5D%3D%5Csum_%7Bx%7DxP%28X%3Dx%29)
![E[X]=0P(X=0)+1P(X=1)+2P(X=2)](https://tex.z-dn.net/?f=E%5BX%5D%3D0P%28X%3D0%29%2B1P%28X%3D1%29%2B2P%28X%3D2%29)
..... (1)
First we calculate the value of P(X=2).
P{X = 2} = P(1st heads and 2nd heads)
= P(1st heads)P(2nd heads)
![P(X=2)=P(A)P(B)](https://tex.z-dn.net/?f=P%28X%3D2%29%3DP%28A%29P%28B%29)
![P(X=2)=(0.6)(0.7)](https://tex.z-dn.net/?f=P%28X%3D2%29%3D%280.6%29%280.7%29)
![P(X=2)=0.42](https://tex.z-dn.net/?f=P%28X%3D2%29%3D0.42)
Substitute P(X=1)=0.46 and P(X=2)=0.42 in equation (1).
![E[X]=0.46+2(0.42)](https://tex.z-dn.net/?f=E%5BX%5D%3D0.46%2B2%280.42%29)
![E[X]=1.3](https://tex.z-dn.net/?f=E%5BX%5D%3D1.3)
Therefore the value of E[X] is 1.3.