Answer: 60 cm.
Explanation:
We can use a ratio table to solve this. We know that 0.6 cm is the same as 3 meters. Yet, how many cm represent 300 meters? So far, we can set up over ratio table like this.
CM: 0.6, ?
M: 3, 300
What did we have to multiply to 3 to get to 300? 100. What we do to one area of the ratio table, we must do the same to the other. We have to multiply 0.6 by 100.
0.6 x 100 = 60
His model has to be 60 cm tall.