Answer: False.
Step-by-step explanation:
Initially, the ratio is 2:7
This means that if we have 2 red marbles, we must have 7 yellow ones.
The quotient here is 7/2 = 3.5
Now, if you add 3 marbles of each colour, then we have:
2 + 3 = 5 red marbles
7 + 3 = 10 yellow marbles.
Now the ratio is 5:10
This means that for every 5 red marbles, we have 10 yellow ones.
But now we can divide both numbers by the same positive integer, because they have a common factor equal to 5.
5/5 = 1
10/5 = 2
Then we have:
5:10 = 1:2
So the new ratio is 1:2
Then the ratio changed when we added the new marbles, which means that Maria was wrong.