Determine if the statements below are true or false. (a) the area vector a of a flat, oriented surface is parallel to the surface. true false (b) if s1 is a rectangle with area 1 and s2 is a rectangle with area 2, then 2 f · da s1 = f · da s2 . true false (c) if s is the unit sphere oriented outward and f · da s = 0 then f (x, y,z) is perpendicular to x i + y j + z k at every point of s. true false

Atechnician compares repair costs for two types of microwave ovens (type i and type ii). he believes that the repair cost for type i ovens is greater than the repair cost for type ii ovens. a sample of 6767 type i ovens has a mean repair cost of $79.79$⁢79.79. the population standard deviation for the repair of type i ovens is known to be $19.18$⁢19.18. a sample of 5555 type ii ovens has a mean repair cost of $75.24$⁢75.24. the population standard deviation for the repair of type ii ovens is known to be $21.40$⁢21.40. conduct a hypothesis test of the technician's claim at the 0.050.05 level of significance. let μ1μ1 be the true mean repair cost for type i ovens and μ2μ2 be the true mean repair cost for type ii ovens. step 2 of 4 : compute the value of the test statistic. round your answer to two decimal places.