Question

18. Grocery sales analysts have approximated that 40% of all people use coupons when shopping. A random sample of 150 grocery shoppers results with Sl that use coupons. To the 5% significance level whether there is sufficient evidence to show that the claim of 4012 inaccurate. Use the z-version of this hypothesis test. 19. Complete Exercise #18 using Minitab. Print out the Session Window and check the answer wil that of Exercise #18. Be certain to use and interpret the p-value that Minitab generates to make the decision 20. It is generally held that if 30% of the macroinvertebrates in limestone-based streams are Stoneflies, then the water quality in the stream is excellent. To analyze the "health" of a particular stream, a random sample of 300 macroinvertebrates is collected. Of the 300 sampled "critters", 65 are stoneflies. Test at the 1% significance level whether this stream is "healthy". In this case, "unhealthy" would be less than 30% stoneflies. Use the z-version of this hypothesis test

18 and 20

Answer 1

18. Let; p - Population proportion of Coupen users. shopping. Sample proportion ; nor sample size. To test; Ho: p=0.40 us H2 p + 0.40 Test Statistica 0.40 N. داره )M D. 40 x (-0.40) n c n =150. 150 = 0.34 0.34-0.400 obsd Za 0:40 x 2-0 40) V 150 - <115 L=0.05 Reject to lift lobs zl > Taa Torges = {0.05 = 1.96 9 Since; lobs Z) is less than 1.96 wee reject to fail to

There is insufficient evidence to conclude set 5% level of significance based on given samples that 40% is inaccurate claim.

20 px Population proportion of macroinverteb. limestone based streams are Stoneflies and stream is healthy. & sample proportion. na simple size. To test; Ho. p=0.30 vs Hi! p <0.30 n=300; 300 Test Statistied- 7= ß-Po ko (-o) to 4 (01). n obed. 2 0-2167 -0.30 == -3,1484. OBOX (1-0,30 300 Reject to iff toks zl > Ta ; a=0.01 20.01 - 70,005 = 2.576. Since soks 217 2-576 we reject to Then we conclude at 1% level of sign Picance that the stream is cunhealthy as all seeject to based on the given sample ce CA