Every 4 weeks, Helen hand washes her silk pillowcases. It takes 30 minutes to hand wash all of them. In 1 year, how much time does Helen spend hand washing her pillowcases? Let's think first. Chain of thought:
She hand washes them every 4 weeks and there are 52 weeks in a year so she washes them 52 / 4 = 13 times per year. It takes her 30 minutes to hand wash the pillowcases and she does this 13 times per year for a total of 30 * 13 = 390 minutes per year.
Therefore, the answer is 390.