Probability and Statistics Mid - II, April - 2012

1.If for two samples S12= 666.67, S12=1109.33 then F is
  • 1.66
  • 3.25
  • 1.25
  • None
Answer: A
2.Range of t-distribution is
  • (-α, α)
  • (-α, 0)
  • (0, α)
  • None
Answer: A
3.Chi-square distribution is
  • Continuous
  • symmetrical
  • multimodal
  • None
Answer: A
4.The Coefficient of correlation=
  • Has no limits
  • can be less than1
  • can be more than 1
  • varies between -1,+1
Answer: D
5.The regression lines cut each other at the point of
  • Average of X&Y
  • average of X only
  • average of Y only
  • None
Answer: A
6.Suppose the inter arrival time is 15 minutes and inter service time is 10 minutes. The traffic intensity is
  • 4/5
  • 5/4
  • 15/10
  • 10/15
Answer: D
7.If λ=8 & μ=12 per hour, the average time spent by a customer in the system is
  • 10 minutes
  • 12 minutes
  • 15 minutes
  • 20 minutes
Answer: C
8.Which of the following matrixes are stochastic?
  • 1 0 0 0 1 0
  • 1 0 0 1
  • 0 1/3 0 1/4
  • None
Answer: B
9.In the transition matrix of the Markov chain if Pij=0 denotes.
  • System is moving from j to I
  • system is moving from i to j
  • Transition is impossible
  • transition is possible
Answer: C
10.In the model of (M/M/1):(α /FIFO), the expected no. of customers/units in the system is given by
  • Ls = λ/(μ-λ) = ρ/(1-ρ)
  • Lq = ρ/(1-ρ)
  • Ls = ρ/(1-ρ)
  • None
Answer: A
11.The formula of the traffic intensity is ………………………..
Answer: λ/μ
12.The probability of exactly one arrival in Δt time is ………………..
Answer: λΔt
13.If the customer leaves the counter due to some reason, it is called…………..
Answer: Reneging
14.A stochastic matrix P is said to be regular if all the entries of some power Pm are ………………….
Answer: Positive
15.Let A =      0      0     1
                1/2   1/4  1/4
                0      1     0

matrix is Regular / not regular..............................
Answer: Regular
16.Two or more independent variables in a regression equation, it is known as ………………………….
Answer: Multiple regression
17.When two regression lines coincide then R =………………..
Answer: 1
18.One regression Co-efficient is positive then the other regression Co-efficient is………………….
Answer: Positive
19.The t-test is applicable to samples for which n is ………………..
Answer: n<30
20.If X = 47.5, μ = 42.1, S = 8.4, & n = 25 then t =……………………
Answer: t = 3.21