Question

9. Is there a difference in the yields of different types of​ investments? The accompanying data provide yields for a​ one-year certificate of deposit​ (CD) and a​ five-year CD for 25 banks.

a. Construct a 90​% confidence interval estimate for the mean yield of​ one-year CDs

b. Construct a 90​% confidence interval estimate for the mean yield of​ five-year CDs.

Bank   One-Year CD   Five-Year CD
1   0.40   4.95
2   0.65   5.00
3   0.90   5.10
4   0.35   3.40
5   0.35   4.15
6   0.35   3.85
7   0.65   3.75
8   2.10   4.40
9   0.65   4.75
10   0.55   4.20
11   0.30   4.45
12   0.60   3.60
13   0.40   4.20
14   0.60   5.10
15   1.80   4.15
16   1.10   4.35
17   1.50   5.00
18   2.20   4.55
19   1.10   5.00
20   0.90   4.45
21   0.60   4.45
22   0.50   4.05
23   0.35   3.45
24   1.15   4.45
25   2.05   4.00

Answer 1

using minitab>stat>asic sgtat>one sample t

we have

One-Sample T: One-Year CD, Five-Year CD

Variable N Mean StDev SE Mean 90% CI
One-Year CD 25 0.884 0.598 0.120 (0.680, 1.088)
Five-Year CD 25 4.352 0.509 0.102 (4.178, 4.526)

a. 90​% confidence interval estimate for the mean yield of​ one-year CDs is 0.680,1.088

b. a 90​% confidence interval estimate for the mean yield of​ five-year CDs. is 4.178,4.526