CPCTC - Corresponding Parts of Congruent Triangles are Congruent
Step-by-step explanation:
When two triangles are congruent, this means they have the same shape and the same size. To have the same shape, each angle must be congruent. To have the same size, each side length must be congruent. When you know two triangles are congruent you can say each corresponding part of congruent triangles is congruent. This is known as CPCTC.
Since 12 out of 30 marbles were black, you can assume that the percentage of black marbles in the bag is 40% (Ex: 12/30=.4) The probability that the marble you pick is black is equal to the percentage of black marbles in the bag. 40% is equal to 2/5.
