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Discrete random variables — Question 55

Original QCE Vault practice · 1 mark

Q55 · Practice questionTechnology-freeSimple familiar1 mark

QUESTION 55

A discrete random variable

X

has

P(X=0)=0.25

,

P(X=1)=0.50

and

P(X=2)=0.25

. Determine

\operatorname{Var}(X)

.

(A)

0.25

(B)

0.50

(C)

0.75

(D)

1.00

ABCD

Question linkSyllabus coverage

WORKED SOLUTION

Answer B

1 mark

ANSWER

B

Worked solution

E(X)=1

and

E(X^2)=1.5

, so

\operatorname{Var}(X)=1.5-1^2=0.5

.

Selects the correct option.

[1 mark]

Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.

View the QCAA syllabus

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