STA1502 Assignment 1 answers

Consider the following independent random samples drawn from two normal
populations. Assume that the two population variances are equal.


Sample 1 Sample 2
The sample size 16 13
The sample mean 34.6 32.2
The sample standard deviation 4.8 5.9


The e-tutor wants to determine whether there is a difference between the two
population means.
The 99% confidence interval of population mean difference is.




Select one:

1.
(12.176;16.796)


2.
(2.4; 14.576)


3.
(-1.491; 6.342)


4.
(-12.176; 16.976)


5.
(-1.674; 4.678)




A statistician wants to determine the reaction of drivers to sudden increase in the price
of fuel. The following data were the speeds of cars (km/h) as the drivers were passing at
a station before and after the price increase. Assume that the two populations are
normally distributed.

, Table
Speeds before price increase Speeds after price increase
43 32
36 33
31 36
30 31
28 32
36 29
27 28
36 39
35 26
30 30
32 32
36 30
Can the statistician conclude that the speed of cars differs?
The 99% confidence interval of the mean speed difference speeds of cars is




Select one:

1.
(-2.909; 6.575)


2.
(2.099; 6.755)


3.
(-2.831; 6.497)


4.
(2.381; 6.974)


5.