Answer:
0.74
Step-by-step explanation:
Of the 30% of boys, 60% arrive by car, that is
60% of 30% = 0.6 × 0.3 = 0.18
Since 30% of the children at school are boys, then 70% are girls.
Of the 70% of girls, 80% arrive by car, that is
80% of 70% = 0.8 × 0.7 = 0.56
Probability of choosing a child from the school is
P( boy ) or P(girl) = 0.18 + 0.56 = 0.74