Every 3 months the arena's musical equipment needs safety checking. look at a comparison of the last 4 years' service costs. mean range year 1 ? 630 ? 300 year 2 ? 672.50 ? 80 year 3 ? 751.25 ? 67 year 4 ? 597.50 ? 350 each year the service was carried out by a different company. in which year was the service costs the cheapest? which year's prices were the most consistent?

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.