Answer:
The mass of the meter stick is 50 g.
Step-by-step explanation:
make a sketch of the problem statement;
0-------------------------------------------------75cm------90cm-----100cm
↓ Δ ↓
W 250 g
where;
W is the mass of the meter stick
Apply the principle of moment; take moment about the pivot.
sum of the anticlockwise moment = sum of the clockwise moment
W(75 - 0) = 250(90 - 75)
W(75) = 250(15)
W(75) = 3750
W = 3750 / 75
W = 50 g
Therefore, the mass of the meter rule is 50 g.