Annie ordered cotton t-shirts for the doubles club. the tree diagram below shows the color and sizes of all the shirts she ordered.

There are 35 red shirts. 5 are large, and 30 are small. 

A:
The question asks for the probability of getting a large red shirt. Because the red shirt is a given, this means that the probability will be given by the following fraction:

large shirts / total shirts

There are 5 large shirts out of 35 total red shirts. Set up the fraction and solve it:



Multiply by 100 to convert into a percentage:



To round to the nearest tenth, look at the hundredths digit:

8 > 5
14.28 -> 14.3

There is a 14.3% chance that Annie will pick a large red shirt.

B:
The question asks for the probability of getting a red shirt, and the shirt being small. There are 35 red shirts out of 100 total, and of those 35 red shirts, 30 are small. Multiply the probabilities of both occurrences happening:



Multiply the decimal by 100 to convert into a percentage:



There is a 30% chance that a randomly chosen red shirt will be small.