Question

g A control group of 14 vehicles using regular gasoline showed mean CO2 emissions of 679 pounds per 1000 miles with a standard deviation of 15 pounds. At α = 0.05, in a left-tailed test (assuming equal variances) the test statistic is: Group of answer choices

Answer 1

0.236

Explanation:

Given :

x1 = 667 ; n1 = 10 s1 = 20

x2 = 679 ; n2 = 14 s2 = 15

Test statistic :

(x1 - x2) / √[Sp² (1/n1 + 1/n2)]

The pooled Variance, Sp² :

Sp² = [(n1 - 1)s1² + (n2 - 1)s2²] / (n1 + n2 - 2)

Sp² = [(9*20²) + (13*15²)] / (10+14-2)

Sp² = 6525 / 22 = 296.59

T = (667 - 679) / √(296.59*(1/10 + 1/14)

T = -12 / 50.844

T = 0.236

Test statistic = 0.236