For
the first three questions say which of the following statements is wrong.For the remainder, state which answer is correct.
Q1.
A nonparametric test
Q2.
In acceptance sampling,
Q3. A
probability density function f(x)
Q4.A
continuous random variable has the probability density function f(x) =
1/3, for x between – 1 and +2, and 0 elsewhere. Its mean, variance
and median are:
Q5.
The standard deviation of the random variable X whose probability density
function is
f(x) = kx(4 – 3x) between x = 0 and 1 is
Q6.
The median of an exponential distribution whose mean is 3 is:
Q7. The
random variable X has a normal distribution with mean 5.75 and variance
2.56. The probability that X lies between 5.5 and 6.5 is
Q8.In a production process there are three phases
P, Q, R, carried out one after the other without delay. The times (minutes)
taken for these follow independent normal distributions, with means and
variances (8, 9) for P, (6, 4) for Q and (11, 3) for R. The probability
that an item from this process takes more than 30 minutes to produce is:
Q9.
The time (minutes) taken to reach working temperature after a piece of
machinery is switched on follows a normal distribution. The probability
of taking more than 5 minutes is least when the mean and variance are:
Q10.A
normally distributed random variable is thought to have mean 7. Its variance
is assumed to be 5. The mean of a random sample of n observations from
this distribution is 6.28, and is used to test the null hypothesis “µ
= 7”. The result of the test is just on the borderline of significance
at the 5% level in a two-tail test. The sample size n is:
Q11.
Two sports clubs run three teams each, first, second and youth. At the
end of a season Club L’s teams have won 65 out of 110 games and
Club M’s teams have won 42 out of 96 games. The standard error of
the difference between the proportions of games won is:
Q12.
In hypothesis testing, a normal approximation may NOT be used for
Q13.
Two independent random samples are drawn from normal distributions with
means µ1, µ2 and the same variance s2, which is not known.
One sample, consisting of 8 observations, has mean 24.25 and the standard
error of the mean is 2.031. The other sample, consisting of 12 observations,
has mean 27.33 and the standard error of the mean is 1.555. The degrees
of freedom and the p-value for a two-tail test of the Null Hypothesis
“µ1 = µ2” are