Question

PART 2: Which test-statistic, z, t, or neither? A candy factory that produces chocolate bars claims each bar weighs 50 grams, at least that is what is printed on the label. Of course, there is bound to be a little variation. An inspector randomly chooses 9 bars from one day's output of 4000 bars. The average weight of the 9 bars is only 47 grams with an SD of 3 grams. The inspector wishes to test the null hypothesis that the factory is doing what it is supposed to on this day. You can assume that the weights follow the normal curve. f. Which significance test should be used? Incorrect A z-test because the SD of the population is known and the weights follow the normal curve. Incorrect A t-test because the SD of the sample is known. Correct: A t-test because the SD of the population is unknown, the sample size is less than 25 and the weights follow the normal curve. Computer's answer now shown above. You are correct. Your receipt no. is 167-1988 Previous Tries g. Do you need to use SD to estimate the SD of the population? Incorrect No, we're given the SD of the population, we don't need to estimate it. Correct: Yes, because with only 9 observations the sample SD is not a great estimate of the true population SD. Computer's answer now shown above. You are correct. Your receipt no. is 167-9407 ? Previous Tries h. Compute the correct SE (either SE or SE). (Give your answer to two decimal places) Submit Answer Incorrect. Tries 2/5 Previous Tries i. Compute the test statistic. (The test statistic is either t or z). Round your answer to 2 decimal places. Submit Answer Incorrect. Tries 1/5 Previous Tries j. How many degrees of freedom are there? Submit Answer Tries 0/5

Answer 1

Let M be the population weight of a bar. Claimis uis 50 grams. i Hoi M = 50 us tha M 750 we have n=9. X = 47 and 5= 3. h. Standerd Ever - SE - B IA il Test statistie is . t to (E-H) - Ja (47-50). ;) degrees of freedom : (n-1) = (9-1) = 18 4) P value = 2xPLt<- 3 1 = 0.0171 (from t table) yes, P-value is less than 5% as 0.0171 < 0.05. 1 as P value less than 5%. : Reject the Null, it's very unlikely that the factory is making the candy bars 50gm as they claim.