Question

A statistical analyst for the Wall Street Journal randomly selected six companies and recorded both the price per share of stock on January 1, 2009 and on April 30, 2009. The results are presented below. Suppose the analyst wished to see if the average price per share of stock on April 30, 2009 is greater than the average price per share of stock on January 1, 2009 at α=.025.

Apr. 30, 2009	33	33	34	30	33	38
Jan. 1, 2009	21	25	30	33	23	27

For the hypothesis stated above, what is the P-value?

	a.	.025 < P-value < .05
	b.	None of the answers is correct
	c.	.95 < P-value < .975
	d.	.01 < P-value < .025
	e.	.001 < P-value < .005

Answer 1

Sol:

Ho:mu1=mu2

Ha:mu1>mu2

create 2 vectors Apr30 2009 and Jan 1 2009

and t.test function in R studio to get t and p value

Rcode:

Apr30_2009 <- c(33   , 33   , 34   , 30   , 33   , 38)  
Jan_1_2009 <- c(21   , 25   , 30   , 33,   23   , 27)

t.test(Apr30_2009,Jan_1_2009,alternative = "greater")

Outout:

Welch Two Sample t-test

data: Apr30_2009 and Jan_1_2009
t = 3.3245, df = 8.024, p-value = 0.005212
alternative hypothesis: true difference in means is greater than 0
95 percent confidence interval:
3.086152 Inf
sample estimates:
mean of x mean of y
33.5 26.5

t=3.3245

p= 0.005212

p<0.025

Reject Ho

Accepty Ha

b.	None of the answers is correct