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Published byDarrell Archibald Anthony Modified over 9 years ago
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Nora and Mara bought 6 items for $207. One item cost $1. All other prices were different prime numbers (in whole dollars only), and each digit (1-9) was used once and only once. The sum of the digits of one item totaled 7, and the price of one pair of pants was $67. What was the cost of the most expensive item?
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I listed the numbers 1-9 1,2,3,4,5,6,7,8,9 B/c the numbers were the costs of the 6 items
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Then, since I have the costs of the two items….. $67 and $1, I can’t use those numbers anymore because I only use the numbers 1-9 once 1,2,3,4,5,6,7,8,9
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After that, the problem said one of the costs’ digits had a sum of 7, so I began with the digits 3 and 4 1,2,3,4,5,6,7,8,9 So to keep in mind that the costs all had to be prime numbers, I couldn’t do the number 34 because that was divisible by 2. So I went with 43 So now I have $1, $67, and $43- 3 more numbers to go
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So next, I added the totals I had so far to see how much more money was needed and to make sure I didn’t go over $207 1+67+43= $111 1,2,3,4,5,6,7,8,9 I picked 8 and 9 because they are the largest numbers and I’m trying to find the most expensive item Nora and Mara bought. I couldn’t use 98 because it was a composite number so I went with 89 So then I added the numbers I had for the costs of the items 1+67+43+89= 200
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So now all I need is 7 more dollars to equal the total of $207 1,2,3,4,5,6,7,8.9 I only had 4 prices figured out and I needed 2 more to get my answer and the 2 numbers had to equal 7. My last two numbers were 5 and 2, so those were the cost of the last 2 items 1+67+43+89+5+2= $207
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I went over my answers to see which was the most expensive item…. $1, $67, $43, $89, $5, $2
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