A computer laboratory manager was in charge of purchasing new battery packs for her lab of laptop computers. She narrowed her choices to two models that were available for her machines. Since the models have similar costs, she was interested in determining whether there was a difference in the average time the batter packs would function before needing to be recharged. She conducted two independent samples and computed the following information:Battery Pack Model 1

(population 1)

Battery Pack Model 2

(population 2)

Sample Size30

30

Sample Mean6 hours

6.8 hours

Standard Deviation1.8 hours

1.6 hours

Which Excel will calculate the test statistic?

a.=(6.0 - 6.8)/(SQRT(1.8/SQRT(30)+1.6/SQRT(30)))

b.=(6.0 - 6.8)/(SQRT(SQRT(1.8)/30+SQRT(1.6)/30))

c.=(6.0 - 6.8)/(SQRT(1.8^2/30+1.6^2/30))

d.=(6.0 - 6.8)/(SQRT(1.8/30+1.6/30))