Answer:
The probability of seeing a person wearing black shoes before seeing a person wearing white ones = 60%
Step-by-step explanation:
People watched walking down the street = 100%
People wearing black shoes = 1/2 = 50%
People wearing white shoes = 1/3 = 33.33%
People wearing red shoes = 1/6 = 16.67%
Probability of black shoes to white shoes = percentage of persons wearing black shoes/sum of the percentages of people wearing black and white shoes)
= 50% : 33.33%
= 60% (50%/83.33%)
When expressed in ratio terms, it means that you will see 1.5 (50%/33.33% or 1.5 : 1) persons wearing black shoes before you see a person wearing white shoes.