Multiplication Rules Question

C

CFarron

Guest
#1
At a university in western Pennsylvania, there were 5 burglaries reported in 2003, 16 in2004, and 32 in 2005. If a researcher wishes to select at random two burglaries tofurther investigate, find the probability that both will have occurred in 2004.

Solution
P(C1 and C2) = P(C1) • P(C2|C1) = (16/53) • (15/52) = 60/689

Can somebody please tell me why did they use 16? And where did 15 came from?