单选题 Judy plans to visit the National Gallery once each month in 2012 except in July and August when she plans to go three times each. A single admission costs $3.50, a pass valid for unlimited visits in any 3-month period can be purchased for $18, and an annual pass costs $60.00. What is the least amount, in dollars, that Judy can spend for her intended number of visits?
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【正确答案】 1、49.50    
【答案解析】Judy intends to go to the Gallery 16 times during the year. Buying a single admission each time would cost 16 × $3.50 = $56, which is less than the annual pass. If she bought a 3-month pass for June, July, and August, she would pay $18 plus $31.50 for 9 single admissions (9 × $3.50), for a total expense of $49.50, which is the least expensive option.