PPSC Past Papers of Statistics


(i)  The probability of event given the event B is P(A/B) is equal to P(A) if B is:
(a) any event in sample S (b) sample space S
(c) A ⊂B (d) B is dependent on A


(2)  A student is attempting to log on internet with 0.5 chance of successful attempt in each trial. The
average number of attempts required to log on successfully is:
(a) 1 (b) 2 (c) 3 (d) 4


(3)  For population with heterogeneous groups, the suitable sampling scheme is
(a) Simple Random Sampling (b) Systematic Sampling
(c) Cluster Sampling (d) Stratified Sampling


(4) Height of date trees, say, follow N(8,4)then the third moment about mean is:
(a) 3×64 (b) 4×256 (c) 0×4 (d) none of these


(5)  If two random variables are independent then correlation or covariance zero. If correlation or covariance between two variables X and Y is zero then:
(a) X and Y are independent of one another (b) X and Y may be independent on one another (c) X and Y may be mutually exclusive (d) None of these