Question 7 (3 points) A county with a large population need to know what the average income is for tax purposes. A simple random sample of 1000 household reveals the following information. The average household income for the sample is $21,000. The median income of the sample is $17,000. The SD of the sample is $10,000, Q1 = $11,000 and Q3 = $24,000. Find a 95% confidence interval for the average household income in this county. a. 21,000 + 196, 10,000(1- 10000) 1000 b. 17,000 + 196, 10,000(1- 10000) 1000 10000 c. 21,000+ 1.96- 10000 V1000 d. 17,000 + 1.96- V1000 OA B Oc OD