- Submitted By: junamogha
- Date Submitted: 11/16/2015 8:11 AM
- Category: Technology
- Words: 508
- Page: 3

1. We ask if the attitudes toward fuel costs of 100 owners of hybrid electric cars (X = 76) are different from those on a national survey of owners of non-hybrid cars (μ = 65, σX = 24). Higher scores indicate a more positive attitude.

(a) Is this a one-or two-tailed test?

→ This is a two tailed test.

(b) In words, what are H0 and Ha ?

→ H0: Attitude towards fuel cost of hybrid owners is same as that of now-hybrid owners

Ha : they are different

(c) Perform the z-test.

→z-score = (76-65) /(24/sqrt(100))

= 11/2.4

= 4.5833

z-critical (assuming α = 0.05) = 1.96

(d) What do you conclude about attitudes here?

→ Since z-score is more than z-critical, attitude of hybrid owners towards fuel cost is different from that of non-hybrid owners.

(e) Report your results in the correct format.

→ Null hypothesis that attitude of hybrid owners is same as that of non hybrid owners is rejected at a level of significance α = 0.05.

2. You investigate whether the older or younger male in pairs of brothers tends to be more extroverted. You obtain the following extroversion scores:

Sample 1 (Younger)

Sample 2 (Older)

10

18

11

17

18

19

12

16

15

15

13

19

19

13

15

20

(a) What are H0 and Ha? (b) Compute tobt. (c) With ? 5 .05, what is tcrit? (d) What should you conclude about this relationship? (e) Which of our approaches should we use to determine if this a scientifically important relationship?

Answer:

Since they are in pairs, it would be better to do a paired t-test.

Sample 1 (Younger)

Sample 2 (Older)

Diff

10

18

8

11

17

6

18

19

1

12

16

4

15

15

0

13

19

6

19

13

-6

15

20

5

a)

Ho: There is no difference between extroversion of older or younger males in brothers.

Ha: They are different

b) Sample Size n = 8

x̅ = 3, Standard Deviation s = 4.5040

tobt = 3/(4.5040/√8) = 1.883943

c)

tcrit (for α = 0.05 ( two tailed) and df=7) = 2.364624

d) Since tobt < tcrit null hypothesis cannot be rejected. Extroversion of elder or...