For some positive value of x, the probability that a standard normal variable is between 0 and + 2x is 0.1255 . The value of x is:
a. 0.99
b. 0.40
c. 0.32
d. 0.16
e. 0.44
Q. 2Regardless of the degrees of freedom, every t-distribution is symmetric around zero.
Indicate whether the statement is true or false
Q. 3For some value of z, the probability that a standard normal variable is below z is 0.2090 . The value of z is:
a. 0.81
b. 0.31
c. 0.31
d. 1.96
e. 1.62
Q. 4When the necessary conditions are met, a two-tail test is being conducted to test the difference between two population proportions. If the value of the test statistic is 2.05, then the p-value is:
a. 0.4798
b. 0.0404
c. 0.2399
d. 0.0202
e. 0.1982
Q. 5For some positive value of z, the probability that a standard normal variable is between 0 and z is 0.3770 . The value of z is:
a. 0.18
b. 0.81
c. 1.16
d. 1.47
e. 1.12
Q. 6A sample of size 150 from population 1 has 40 successes. A sample of size 250 from population 2 has 30 successes. The value of the test statistic for testing the null hypothesis that the proportion of successes in population one exceeds the proportion of successes in population two by 0.05 is:
a. 1.645
b. 2.327
c. 1.960
d. 1.977
e. 1.772
Q. 7The probability density function f(x) of a random variable X that is normally distributed is completely determined once the:
a. mean and median of X are specified
b. median and mode of X are specified
c. mean and mode of X are specified
d. mean and standard deviation of X are specified
e. mode and standard deviation of X are specified
Q. 8For testing the difference between two population proportions, the pooled proportion estimate should be used to compute the value of the test statistic when the:
a. populations are normally distributed
b. sample sizes are small
c. samples are independently drawn from the populations
d. null hypothesis states that the two population proportions are equal
e. populations are normally distributed and sample sizes are small
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