We are given the number of Blue and Purple Marbles for each of the four friends. So first we have to find the ratio of blue marbles to purple marbles for each of them.
A) Rosa
Number of blue marbles = 10
Number of purple marbles = 12
Ratio of blue to purple marbles =
B) Chi
Number of blue marbles = 5
Number of purple marbles = 6
Ratio of blue to purple marbles =
C) Alberto
Number of blue marbles = 5
Number of purple marbles = 12
Ratio of blue to purple marbles =
D) Pedro
Number of blue marbles = 10
Number of purple marbles = 6
Ratio of blue to purple marbles =
From the above calculations we can see that Pedro has the highest value of ratio for blue marbles to purple marbles. Also we can see Pedro is the only one for whom the number of blue marbles is more than the number of purple marbles. So this confirms that our calculation is correct.
Thus, the player which gets to go first is Pedro.