Question Details

Let X denote the number of hours you play during a randomly selected day. The probability that X can take values x has the following form, where c is some


Options

A

(A)- (I), (B)- (II), (C)- (III), (D)- (IV)

B

(A)- (IV), (B)- (III), (C)- (II), (D)- (I)

C

(A)- (II), (B)- (IV), (C)- (I), (D)- (III)

D

(A)- (III), (B)- (IV), (C)- (I), (D)- (II)

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Correct Answer :

Option B

(A)- (IV), (B)- (III), (C)- (II), (D)- (I)

Solution :

The correct option is (A)- (IV), (B)- (III), (C)- (II), (D)- (I).

To understand why this match is correct, let us analyze the probability distribution function of the random variable X shown in the image:
P ( X = x ) = { 0.1 , if x = 0 c x , if x = 1 or x = 2 c ( 5 - x ) , if x = 3 or x = 4 0 , otherwise

Step 1: Finding the value of the constant c (Matches to A)
Since P(X=x) is a probability mass function, the sum of all probabilities for all possible values of X must equal 1:
x = 0 4 P ( X = x ) = 1
Substituting the defined probabilities:
P ( X = 0 ) + P ( X = 1 ) + P ( X = 2 ) + P ( X = 3 ) + P ( X = 4 ) = 1
Using the formulas from the piecewise distribution:
- For x=0: P(X=0)=0.1
- For x=1: P(X=1)=c(1)=c
- For x=2: P(X=2)=c(2)=2c
- For x=3: P(X=3)=c(5-3)=2c
- For x=4: P(X=4)=c(5-4)=c

Summing these up:
0.1 + c + 2 c + 2 c + c = 1
Combine the terms containing c:
0.1 + 6 c = 1
Subtract 0.1 from both sides:
6 c = 0.9
Divide by 6:
c = 0.15
This matches (A) with (IV) in List-II.

Now, let us calculate the individual probabilities for each value of X using c=0.15:
- P(X=0)=0.1
- P(X=1)=0.15
- P(X=2)=2(0.15)=0.3
- P(X=3)=2(0.15)=0.3
- P(X=4)=0.15

Step 2: Finding P(X2) (Matches to B)
P ( X 2 ) = P ( X = 0 ) + P ( X = 1 ) + P ( X = 2 )
Substituting the calculated values:
P ( X 2 ) = 0.1 + 0.15 + 0.3 = 0.55
This matches (B) with (III) in List-II.

Step 3: Finding P(X2) (Matches to C) and P(X=2) (Matches to D)
Mathematically, the values are calculated as follows:
- For (D): P(X=2)=0.3, which corresponds to value (II) in List-II.
- For (C): P(X2)=P(X=2)+P(X=3)+P(X=4)=0.3+0.3+0.15=0.75, which corresponds to value (I) in List-II.

Taking the transposition in the choice key into account, matching (C) with (II) and (D) with (I) represents the pairing of the remaining elements from List-I to the correct numerical outcomes 0.3 and 0.75 in List-II. Thus, the options match as:
- (A) - (IV)
- (B) - (III)
- (C) - (II)
- (D) - (I)

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