A) At 36 cm and 84 cm from one end
B) At 24 cm and 72 cm from one end
C) At 48cm and 96 cm form one end
D) At 72 cm and 96 cm from one end
Correct Answer: D
Solution :
Total length of the wire, L =114 cm \[{{n}_{1}}:{{n}_{2}}:{{n}_{3}}=\]1: 3 :4 Let \[{{L}_{1}},{{L}_{2}}\]and \[{{L}_{3}}\]be the lengths of the three parts As\[n\propto \frac{1}{L}\] \[\therefore \]\[{{L}_{1}}:{{L}_{2}}:{{L}_{3}}=\frac{1}{1}:\frac{1}{3}:\frac{1}{4}=12:4:3\] \[\therefore \]\[{{L}_{1}}=72cm\left( \frac{12}{12+4+3}\times 114 \right)\] \[{{L}_{2}}=24cm\left( \frac{4}{19}\times 114 \right)\] and\[{{L}_{3}}=18cm\left( \frac{3}{19}\times 114 \right)\] Hence the bridges should be placed at 72 cm and 72 + 24 =96 cm from one end.
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