Suppose that you own a coffee shop. You want to estimate the population mean of

Question

Suppose that you own a coffee shop. You want to estimate the population mean of the daily sales. A sample of past 5 days of sales data provided the following information Day 10 94 cups) You are going to use the sample average as a point estimator for the population mean. You also want to measure the accuracy of your estimator, and use the standard error as the measure of the accuracy. What is the standard error of your point estimator? When you calculate a variance or a standard deviation, use the sample version formula. a. Square-root of 4.3 O b. Square-root of 5.3 O c. Square-root of 6.8 d.Square-root of 3.8 e.Square-root of 8.8 points Save Anawer QUESTION 2 One is interested in the percentage of doctors who recommend aspirin rather than other painkilers for their patients with headaches A random sample of 120 doctors resuts in 12 who indicate that they recommend aspirin. erm net» 99% contderon interval for the proportion of doctors whmornnend asprin. Find the nearest anewer 0.16-0.4 and /0.09-0.3 Approxate v120 11 and145 12 C[220%, 17.74%) d.[355%, 1646%) e (900%, 3032%)

Explanation / Answer

1)

std error =square root(sample variance/n) =square root(26.5/5)=square root(5.3)

option B is correct

2)

here sample proportion phat =12/120 =0.1

for n=-120 ; std error =(phat*(1-phat)/n)1/2 =0.0274

for 99% CI ; critical z =2.5758

therefore 99% confidence interval =sample proportion -/+ z*std error =0.0296 ; 0.1704 ~ 2.96% ; 17.04%

option B is correct

S.No X1 X12 1 94 8836.0000 2 100 10000.0000 3 90 8100.0000 4 89 7921.0000 5 87 7569.0000 X 460 X2 42426.0000 s12=(x2-(x)2/n)/(n-1) 26.5

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