How many blue objects there are? How many of them are large?
17/20
Practice makes perfect
The probability that an event will occur, given that another event has already occurred, is called a conditional probability. Since we want to know the conditional probability of selecting a large object given that it is blue, let's highlight the number of large blue objects and the total number of blue objects in the given two-way frequency table.
Large
Small
Totals
Blue
17
3
20
Red
8
12
20
Totals
25
15
40
The condition that the object selected is blue limits the total outcomes to the 20. Of those 20 objects, 17 are large.
P(large | blue)&=Large blue/Blue [1em]
P(large | blue)&=17/20
