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Hemoglobin levels in 11-years-old boys vary according to a Normal distribution with sigma (o) 1.2 mg/dl. How large of a sample is needed to estimate u (population mean) with 90% confidence so margin of error is no greater than 0.5 g/dl? Please show all your work. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). BIUS Paragraph Arial V 10pt V V A v