First of all, ctake into account the total number of hot air ballon, by using the table:
Blue | Yellow | total
1 passenger 2 6 8
2 passengers 7 5 12
total 9 11 20
next, notice that the number of blue hot air ballons with 2 passengers is 7. The probability to select a blue hot air ballon with 2 passengers is given by the quotient in between 7 over the total of the sample 20:
p = 7/20
Hence, the probability is 7/20
