My Friend's Bulky Laptops!
My friend still carries around laptops with him all the time instead of tablets. He has three of them. I couldn't help it but asking him how much do each of them weigh?
He said, "If you multiply their weights in lbs, it will be 72 lbs ."
I scratched my head, "You need to tell me more."
He said, "If you add their weights, it will be the same as today's date."
Hopeful, I looked up the date in my cell phone, and thought for a little bit, but my excitement did not last long.
I told him, "I am still not certain if I know their weights."
He said, "Oh, the lightest one is the fastest."
I smiled 'coz I now knew their weights.
How much do they each weigh?
Due to the limitation that the answer can be only one number, simply write all the digits in ascending order as the answer. For example, if the answer is 3 lb, 5 lb and 9 lb, write 359.
Hints:
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Yes, the problem has all the information you need to find their weights.
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Make sure to apply the information in the same order as it is provided in the sequence of events.
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The weights are in whole number lbs!
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Today's date means the date of the month. For example, if it is Mar. 31, 2015, then he meant 31 lbs as the sum of the weights.
The answer is 266.
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1 solution
First clue, the product is 72. The prime factors of 72 are 2x2x2x3x3. But we need to have only three factors, so the following combinations are possible candidates:
1 1 72
1 2 36
1 3 24
1 4 18
1 6 12
1 8 9
2 2 18
2 3 12
2 4 9
2 6 6
3 3 8
3 4 6
Second clue, their sum is today's date. Here are the sums of these possible combinations:
1 1 72: 74
1 2 36: 39
1 3 24: 28
1 4 18: 23
1 6 12: 19
1 8 9: 18
2 2 18: 22
2 3 12: 17
2 4 9: 15
2 6 6: 14
3 3 8: 14
3 4 6: 13
Now the guy should be able to tell which combination is the answer by matching it with the date .... unless the date is the sum of more than one combination.
The only two combinations with the same sum are 2, 6, 6 and 3, 3, 8, so it must be one of those two.
Then the friend said "the lightest one ...". In 3,3,8 there is no unique lightest laptop, so it has to be 2,6,6 !