Question

Question 1 1 pts Two training procedures are compared by measuring the time that it takes trainees to assemble a device. Two groups of trainees are taught, each using a different method. Is there a difference in the two methods? Assume both populations follow normal distributions with equal variances. Method 1 Method 2 n=10 n2=12 21 = 35 32 = 31 81 = 4.9 S2 = 4.5 Which of the following formula should be used to calculate the standardized test statistic? (21-23)-DO *1+12 0 Z (<1-22)-D O (*1-22)-D - G+) o t= d-Do ad o 1 140

Answer 1

Option 3

t = { (xbar - x2 bar) - D0 } / {s_p * $\sqrt$ {(1/n1)+(1/n2)}}

Since here we are assuming population variances are same, we use standard deviation

Sp ={ (n1-1) * s1^2 + (n2-1)*s2^2 }/(n1 + n2 - 2)

Here the population standard deviation is unknown hence,

t = (xbar - x2 bar) / s_p * $\sqrt$ {(1/n1)+(1/n2)}

will follow t distribution with

degrees of freedom n1 + n2 - 2