(40 points) A shoe store finds that 50% buy sneakers, 45% buy running shoes, and 5% buy hiking boots.
For customers that buy sneakers, 10% return or exchange them. For customers who buy running shoes,
25% return or exchange them. For customers who buy hiking boots, 15% return or exchange them. If a
customer returned or exchanged a pair of shoes, what is the probability they were running shoes?