The length of 3 rods are in the ratio 4 : 5 : 6. If the sum of the weights of the longest and the shortest rod is 10 metres more than the length of the third rod, what is the length of the shortest rod?	Select the correct option:	A) 21m	B) 20m	C) 8m	D) 18m	E) of these
Let the length of the three rods be 4k, 5k and 6k respectively.   4k + 6k = 5k + 10   =&gt; 5k = 10 =&gt; k = 2   Therefore the weight of the lightest boy   = 4k = 4(2) = 8 m.   ANSWER:8m
<result>C</result>
The length of 3 rods are in the ratio 4 : 5 : 6. If the sum of the weights of the longest and the shortest rod is 10 metres more than the length of the third rod, what is the length of the shortest rod?