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January 30, 2015

January 30, 2015

Posted by **scott** on Tuesday, May 13, 2014 at 9:35pm.

Assuming that the two groups have unequal variances, calculate the t-statistic that tests the null hypothesis that the mean lifespan of the two types are equal against the alternative hypothesis that the mean lifespan for the improved batteries is greater than that for the current batteries.

a)1.62

b)7.166

c)-3.682

d)6.907

e)4.923

- statistics -
**MathGuru**, Thursday, May 15, 2014 at 4:33pmWelch's t-test for unequal variances:

t = (mean1 - mean2)/√(s^2/n1 + s^2/n2)

t = (4.31 - 3.68)/√(0.17^2/10 + 0.22^2/10)

t = 0.63/0.08792 = 7.166 (rounded)

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