Elementary Statistics (12th Edition)

a) From the table, the probability of getting exactly 1 failing car is is: $P(X=1)=0.399.$ b)From the table, the probability of getting at most 1 failing car is: $P(X\leq1)=P(X=0)+P(X=1)=0.377+0.399=0.776.$ c)The result from b) because it gives us the probability for the range of 0 to 1 whilst a) only gives us the probability of 1. d) 1 is not an unusually high number of failing cars, because 0.776>0.05.