A metre scale is supported on a wedge at its centre of gravity. A body of weight ' $\mathrm{w}$ ' is suspended from the $20 \mathrm{~cm}$ mark and another weight of 25 gram is suspended from $74 \mathrm{~cm}$ mark balance it and the metre scale remains perfectly horizontal. Neglecting the weight of the metre scale, the weight of the body is

• Correct answer
  A

  20 gram-wt
• B

  15 gram-wt
• C

  33 gram-wt
• D

  30 gram-wt

Solution

Taking moments about the centre of the scale we get $$ \begin{aligned} & \mathrm{W} \times 30=25 \times 24 \\ & \therefore \mathrm{W}=\frac{25 \times 24}{30}=20 \mathrm{~g}-\mathrm{wt} \end{aligned} $$

Hence, the correct answer is option: 'A'.