#### Answer

Confidence interval is 17.49 - 22.51

#### Work Step by Step

From part (c), we have: $z_{α/2} = 1.96$
Margin of error (E) = 1.96 x $\sqrt {(100/100 + 64/100)}$
= 1.96 x 1.28 = 2.51
The endpoints of the confidence interval are:
x̅1-x̅2 - E = 70 - 50 - 2.51 = 17.49
x̅1-x̅2 + E = 70 - 50 + 2.51 = 22.51