Which of the following is not true with respect to tests for the difference between two means when the population standard deviations are known? a. The samples must come from normally distributed populations or the sample sizes must be large enough to apply the central limit theorem. b. The samples must be randomly and independently selected. c. The test statistic for a hypothesis test has a t distribution. d. The margin of error for a confidence interval estimate is

c. The test statistic for a hypothesis test has a t distribution

Explanation:

The test statistic when the standard deviation is known and population is normally distributed should not have a t-distribution. A t-distribution will be required for the test statistic for the hypothesis if standard deviation is unknown and population is also normally distributed. The other options are correct however.

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x