question_answer 1)

                In a model of a ship, the mast is 9 cm high, while the mast of the actual ship is 12 m high. If the length of the ship is 28 m, how long is the model ship?                

Answer:

                Let the length of the model ship be \[x\,\,cm\]. We form a table as shown below:                

	Actual ship	Model
Length of the ship	28 m	\[x\]
Height of the mast	12 m	9 cm

  More the length of the ship, more would be the length of its mast. Hence, this is a case of direct proportion. That is,                 \[\frac{{{x}_{1}}}{{{y}_{1}}}=\frac{{{x}_{2}}}{{{y}_{2}}}\] \[\Rightarrow \]               \[\frac{28}{12}\,=\frac{x}{9}\] \[\Rightarrow \]               \[12x=28\times 9\] \[\Rightarrow \]               \[x=\frac{28\times 9}{12}\] \[\Rightarrow \]               \[x=21\] Hence, the length of the model ship is 21 cm.