I have an unmarked ruler (AD) of length 6cm. Making two marks in it, one (B) at 1cm from the left end and other (C) at 2cm from the right end, I´m able to measure any integer length from 1 to 6 cm:
+----+-------------+--------+
A B C DAB = 1cm / CD = 2cm / BC = 3cm / AC = 4cm / BD = 5cm / AD = 6cm.
If I have an unmarked ruler of length 14cm, what is the minimum number of marks, and where do I have to make them, in order to be able to measure any integer length from 1 to 14cm?
You can use five marks on a ruler of 16 cm.
2 - 5 - 5 - 1 - 2 - 1
_ _ | _ _ _ _ _ | _ _ _ _ _ | _ | _ _ | _
instead of
1 - 1 - 3 - 3 - 3 - 3 - 2
_ | _ | _ _ _ | _ _ _ | _ _ _ | _ _ _ | _ _
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Posted by monica
on 2008-11-16 14:33:06 |
16 cm
